The brilliant thing about Lotuses... Lotii... Lotus cars is that they're built from plucky British spit and tissue and therefore weigh nothing. They've always been the last word in handling due to their innovative nature, a tradition carried on from Chapman and of which I think he'd still be proud.
The terrible thing about Lotu... their cars is that they're built from plucky British spit and tissue and therefore broke incessantly and expensively. I know they're trying to move upmarket and push their cars further up the sportscar food chain, but they'll still offer something very different to Ferrari, despite being run by an ex Maranello boss.
A Dino sub-brand for Ferrari could work really well, especially given the emissions regulations governing the range of cars a brand sells, but Ferrari do lightweight in an expensive way, not by melting down Coke cans and glueing them together. If Dino cars made it to market it will close the gulf between the two brands a little more, but they'll both offer very different cars when it comes to the driving experience, if not the black and white figures.
The Alfa 4C was promised to be 850Kg, but I just can't see it being the case, well, for a realistic price anyway.