I imagine at game launch the full capabilities of magic will be relatively limited compared to what we imagine, given that we typically imagine magic to be capable of doing anything. A big thing to remember is that as magic is a feature that will only really be seen by a minute percent of the population, the chance of them making it as detailed and expansive as we're thinking is unlikely.
Consider that 1/20 have a talent, and that magic is one talent of possibly up to 40 (Just an estimate I've heard of number of talents there will be, no source.) Now that means 1/800 players will have a magical talent. If we're generous and say half of them discover that talent, that means magic is a feature that one out of every 1600 players will actually get to use.
Now consider the intense amount of programming work it takes for basically ever aspect of magic. A Fireball requires a unique animation for creation, travel, and impact, along with programmed physics of how far it will travel, what damage it will do to various structural types, etc. Every single spell in a magic user's arsenal is likely to take a great deal of time to program, animate and test.
Given that so few people will actually have access to the feature, and that every aspect of advancing it is incredibly time consuming, I imagine magic will be fairly limited in is full capabilities at launch. As time passes after launch and more means for unlocking the magic talent are likely to be introduced I believe they will continue adding to it, giving magic users more capabilities. Day 1 wizards though I doubt will have a massive spell library available to them.