Seems interesting, but I wouldn't be surprised if it's just a "menu-space" you can choose your cars in that has cut-scenes for entering/leaving. Not knocking it, just don't expect a Forza title to really go in-depth with the idea.
I never played TDU2, had hours on TDU1 and loved it, but I think only the 2nd let you walk around and really change up your home? TDU1, tmk, let you move to the next car than "walking". Had some really neat touches to promote "ownership".
I think to this day, the PGR series has still set the bar for me with garage spaces. I think 4 got a bit creative and the garages got more crazy with progression, but 2-4 still had really nice ways to display your cars. I loved the dealership in PGR2 that you walked around and test drove in, and PGR3-4 allowing you different home spaces. I don't think FH has to go as far as BC did, but something similar would be nice to see. The Motorsport series has sort of gotten close; FM5 or 6 had a small, personal garage for your car & FM7 had a teaser of the home space littered with cars. I wonder if the computing power is a factor though at displaying and getting really in-depth.