Alright, so after almost a week in TH10 my spell factory is done. It is maxed now and I cannot upgrade it ever again, at least until they release another level. Though given the current balance of TH11/12, I doubt they will give a new level and even if they do, the new level will most probably not increase capacity.
Still waiting on AQ to lvl21. Started 2 army camps now, too bad their diminishing returns really hurt. TH11 and TH12 should gain 6-8 army space instead of 5, that should bring better balance.