Here is the Mustang packages Ford should build. This is just my opinion, not fact, not intended to piss anyone off, just an idea that I have, and incidentally have wanted for about 10 years. this is somewhat compareable to what has already been posted here, but different, and more variable.
Options! Options! Options! Other cars have more options than the late model mustangs have had. The Early mustangs are a paradigm of American cars, and were very option-configurable. New ones are not. You get the three little models that Ford sells, and if you are not happy, then the after-market is your answer, at the cost of your warranty, in most cases. People should be able to build a car from the factory to their taste, and their budget.
Since the '05 Mustang is a re-awakening of the marque, it should fully return to it's foundation by being many cars to many people. That is what founded "Mustang." The new cars are very disappointing in their size, shape, weight, and build quality. Not to mention they are basically updated 78 Fairmonts underneath the skin. The reason the new car has double the torsional rigidity is that the current car is so flexible.
So here's how I see the new model breaking down: All model ranges, except "Track pkg" and Special Editions are available as "SportsRoof" coupes, or convertibles, Track package only with coupe body style, Special Edition depends on the yearly theme, but mostly coupes. The one universal change should be smaller or more sleek side mirrors, rather than those billboards on the show car.
Mustang (base model) MSRP ~$17,995 - highest production numbers
-Standard: 200hp 4.0 V6, 4spd auto or 5spd manual. 16" halibrand-style wheels, Electric windows and locks. cloth interior, plastic dash face panel.
-Additional Options: premium interior (basically up to GT specification) sound system, 5spd Automatic, Torsen or Bosch torque-bias Limited slip diff. (Live axle only) small fog-lights below the bumper. 17" wheels (from GT)
-Performance Package: 4.6 24-valve 300hp V8, 5spd Auto or tremec 5spd manual trans, mandatory GT brakes and spring/dampers. (similar to 87-93 LX 5.0) Base price with Perf. pkg and standard interior would be $19,995. There is your 300hp for under $20,000.
Mustang GT - MSRP ~$24,995 - mainline image and performance model.
-Standard: 300hp 24v V8, 5spd cloth or leather seats, premium interior trim, Aluminum Dash face panel, color-change gauges, etc. (refer to as GT spec.)
5spd automatic, or tremec 5spd manual trans, limited slip live rear axle. Grille-mounted fog-lights and GT appearance package. 17" 5-split spoke wheels. (look like concept car's wheels)
-Optional: t56 6spd transmission. Axle gears: 3:55, 3:73:1. Mach1000 stereo system. 18 inch Cragar-style wheels (see GT show-cars) Red, light Grey, or Blue interior Accents (See red interior on show car) in reference to the tri-color bar of the mustang emblem. Glass roof. (at least a glass sunroof if concept's glass roof is not feasible) Optional fog light delete, optional spoiler delete.
Option Packages:
-RS Package: ~$1,500. Same as GT, same available options, with IRS and 6spd manual or 5spd auto standard. The RS Appearance package includes: RS insignias (rather than GT), wire mesh grille (think Jag S-type R), different air dam with lower fog-lights, smoother rocker panels and rear bumper. similar to SN95 Bullitt ground-effects. The theme of this package is to be a up-market sophisticated car to compete with 350z, G35, BMW 330Ci, RX8, with more horsepower, and lower price. The GT would be the main contender for the drag-race Camaro-fighting customers, and sticks to a live axle. An RS Automatic would be a car for someone who might otherwise buy a Mercedes C320 Coupe.
-Track package: Factory race options. Optional 5.0 DOHC engine. SVT brakes. Lightweight Sheet-moulded compound fenders, cowl-induction hood, trunk lid. Standard 18" wheels. Standard 5spd auto or manual, optional 6spd. Less sound-deadening, fog light delete. optional AC-delete, rear seat delete. Factory lightweight GT (drag pack) **Can be paired with RS Package for IRS and 6spd in a lightweight autocross/road racing spec.
These would be build to order ONLY. they would cost more and would be made in limited numbers on demand. No dealer stock, quite possibly built by SVT.
Mustang Special Edition MSRP - ~$28-29,995. Yearly special models in limited numbers, like Boss 5.0 or Boss 5.4, Mach 1, Bullitt, etc. Instant collectors items.
5.0 DOHC (~350hp) Standard, Manual trans only. Big brakes, lowered springs, Live Axle or IRS, 5 or 6spd Manual trans depending on theme of that year's special edition. Custom paint and body details depending on theme. Full interior options standard. Possibly "Track pack" options similar to GT/RS.
SVT Mustang. (Possibly commemorative Shelby nameplate like GT350, could be Cobra, but I wouldn't mind if they went away from that name on the mustang-based cars) - ~$34,995, limited production. A step above RS and Special Editions,
Supercharged 5.0 DOHC engine with more than 400hp. IRS and 6 spd standard. Bilstein or Koni dampers, lower springs, larger anti-roll bars. Body-colored Dash face panel, special seats (possibly Recaros) gauges, and trim. Optional rear-seat delete.
SVT appearance package would include a grille with center-mounted foglights (68 Shelby) deeper front air dam and splitter, flat floor-panels with ground effects. rear diffuser, and central exit exhaust. lower rocker panels, functional brake ducts in front, and side-scoops, Leading edge ducts in hood (like Concept car) with cold air intake, heat extractor ducts in rear of hood (69 shelby) Horizontal tail-lights in rear, (like concept and all Shelbys) and louvered or filled in quarter windows, duck-tail spoiler. Optional tape stripes. Offered in charcoal with silver stripes. (Eleanor) and 19" halibrand-style or Magnum500 style wheels. This car would be the figure-head, and compete with the GTO and approach the Corvette. Would provide an in-house hot-rod, to compete with specialty cars like Saleen, Steeda, and Roush, which may end up going up-market, firmly into Corvette territory.
That would provide 6 distinct models (counting v6 and base v8 separately, GT and RS pkg separatel, not counting track pkg cars separately.) and would be the most diverse RWD sports coupe on the market, and the only one that really caters to ameteur road AND drag racers with a factory lightweight, and to younger buyers with a V8 5spd base model. Options could get expensive, but the base model and GT should have good standard features for their prices. Each model may see slightly fewer sales, but averaged together, I think it would sell over all very, very well by catering to many different buyers, much as the original did.
as for me, I would take a theoretical Mustang RS 6spd (because of the IRS), or a full-on Shelby GT350, depending on cash being tight or not.
Have fun dreaming. Maybe It'll come true.
Punch out 300hp on a i-4 and pop it into a stang again, unless the weight of the new ones is to much to push around and still be serious. 
