The 6th generation Camaro being lighter is pretty much a done deal, its a big reason why its going on the alpha platform.
The Cadillac ATS (first alpha car) has a stated curb weight of less then 3,400 pounds at least with the 2.5L 197BHP I-4 engine. Also they already stated that the 6th generation Camaro is to use the ATS sedan wheel base, as the ATS coupe will have a shorter wheel base.
Though the 6th generation Camaro is likely to pack the 2.0L turbo engine that produces 272BHP @ 5,500rpms and 260ft-lbs @ 1,700rpms. The current Camaro with the 3.6L LFX engine produces 323BHP and weighs in at 3,750 pounds. 11.6 pounds per horsepower, and if the 6th generation Camaro with the 2.0T engine were to weigh in at 3,400 pounds. It would have a power to weight ratio of 12.5 pounds per horsepower, so not as good as the 5th generation with V-6 engine. However the other .9 pounds per horsepower can be made up in other areas, for example 8 speed automatic and 7 speed DSG gear box. Improved aerodynamics would also go a long way to helping to bridge the gap and also bumping the horsepower of the 2.0T engine. If it produced 290BHP it would have a similar power to weight ratio as the 5th generation LFX V-6 Camaro and add to that 8 and 7 speed transmission. You could produce a 6th generation Camaro that gets better fuel economy, is faster, and much more of a drivers car when compared to the 5th generation car.
Whats to not like, for one some people really like the sound of the LFX V6 engine (I am actually one of them). Some people do not like the sound of I-4 engines even I-4 turbo engines and some see I-4 engines purely as something pedestrian.
From videos of the ATS with the 2.0L turbo I actually like the way that engine sounds and wouldn't mind it. The notion of a Camaro faster then the current V-6 Camaro but can get say 35MPG on the highway I find to be an impressive engineering feat.
Even more so the next generation Camaro with a gen 5 SBC under the hood should also be impressive and I can't wait to see that either.