I'm with TA on this one. Forces is clearly being marketed to the younger demo and Mania is being marketed to the older demo.
The smartest thing ever is that they clearly separated the two. Now they're free go to the extremes without having to consider much for including the alternative demographic.
Mania will be fully classic, Forces will be fully modern. Whatever side of the Sonic fandom you are, you'll be playing a new game this year that will have everything you want and none of what you don't. If you like both styles, you'll be playing both. Genius.
The only thing that betrays this approach is the fact that classic Sonic is a play-style in Forces. Can't wrap my head around that choice yet, but we'll see how it all plays out.