I definitely understand what your saying, but disagree to some extent. If I was in charge of mitsu i'd release the following line up:
-Eclipse gst and gsx both with 245hp. The gsx would be on par with the wrx in terms of performance but leaving weak ends so it doesn't compete with the evo (brakes, tranny, etc)
-3000gt vr4. With the old 3000gt being more of a sport touring car, I would do the same again. Give it 350-400hp, make it more of a "premium" car that older men want to cruise the freeways the mountain passes. It wouldnt handle like the evo or compete in the same category. It would hopefully capture a older demographic. It would also have a higher price tag.
-Evo. This could be left as it, as its a self sustaining car. It has its followers and those that bounce between subaru and mitsu.
Galant- Just make this car your nicer eco car. Use this model to capture the accord and camry crowd
Mirage- this is your bottom of the barrel car. It would compete with carolla and similar.
Mitsubishi would need to hire a new marketing team and refresh the company in my opinion. I would highly structure my commercials after the extremely successful Dominos commercials. If they can come on tv and say we realized our companies quality sucked, and we fixed the problems, come in and test drive the new mitsu.... I think you would put mitsu back on track. Something like "mitsubishi... reborn".
The problem with doing this, is of course R&D for new cars takes a lot f money. Money that mitsubishi probably doesnt have. But if they did, I really think they could emerge as a really powerful player in the car industry.