Thus we will end up with, in my opinion, a lardy American inspired mustang looking thing, with a rubbish interior and mediocre performance from some kind of EcoBoost I4 engine. Not that I have an issue with fords new engines, they are awesome, just not in a mustang!
That may happen - but it's not the plan. This is another of Ford's "world cars" - like the Mondeo/Fusion and Focus. It's a car designed to work in all markets with only minor changes for individual markets.
It will be interesting to see how they manage to maintain some form of traditional Mustang heritage while making it attractive to all.
Could be a big win or a big lose for Ford imo.