That's about the same number of units as Starcraft has. The strategies involved will depend on making sure these units are substantially different (Which right now, they're not).
As strategies develop, more units will come into play. But it was never a strength to have robotic vs. vehicle versions of the same units in TA/SupCom.
In Total Annihilation, for instance you had a very finite # of actual units:
- Flash tank
- Stubby (Forgot its name but basically a slower light tank with a projectile)(
Then it has tier 2 units that were effectively the same units but bigger and tougher (I used the missile launcher tank massively which was very effective).
Later on, after release, more units were released that started to expand on these. You got flak tanks, radar tanks, radar jamming tanks, actually distinct Kbots, tanks that could go over water, etc. But these aren't part of the game on day 1.
With Ashes, we want to start with a dozen+ differentiated units and then add more as new strategies manifest.