Hey there, Having more wizards available on your account may be possible, but will be a huge financial problem for Kingsisle, having to suddenly give more space for all 5 million accounts all at once. It may come eventually, but it is unlikely.
As for schools, I doubt many more if any will come. We already have the 7 Starter schools (split into , and , and then ) and along with those we have the Astral schools. () which act as enhancements to your spells if you didn't know.
And just a year ago KI added Magic. Shadow magic is, like I said, still fairly new and hardly has any spells to it. Kingsisle will most likely continue with shadow magic till it has tons of spells before even considering ever adding more schools to the game. We have 11 schools of magic total with 7 possible as primary. I doubt any more will ever be added, especially to the primary list, but its not entirely out of the picture for new schools to be added in the future. Hope I helped.
, and 
, and then 
) and along with those we have the Astral schools. (
) which act as enhancements to your spells if you didn't know.
Magic. Shadow magic is, like I said, still fairly new and hardly has any spells to it. Kingsisle will most likely continue with shadow magic till it has tons of spells before even considering ever adding more schools to the game. We have 11 schools of magic total with 7 possible as primary. I doubt any more will ever be added, especially to the primary list, but its not entirely out of the picture for new schools to be added in the future. Hope I helped.