So my guess is Sonic Mania will have 10-12 Zones with 20-22 acts and 21-23 boss battles.
I would be more than happy with this, I feel like 10 - 12 zones is a good length.
Also, gotta say I am not a fan of the general 'dark' 'edgy' tone they're taking Sonic Forces, I felt like the self aware comedic direction is way better for Sonic in general. HOWEVER, it wont stop me enjoying the gameplay if it plays like Generations and Colours which imo is the perfect 3D Sonic design.
In the end, Sonic Mania is what's really exciting me though... There really hasn't been a Sonic game like this in so long. I'm so eager to get stuck back into genuine feeling classic Sonic enviroments, music, gameplay...