There is really no limit to it. I mean I don't think it will ever be %90 or whatever but I think it is quite limitless how far it can go up or go down. There is literally no barrier that just stops it when it reaches to something. It can go up or down but never really change anything in the market.

When bitcoin goes up, sometimes other coins "go down" in bitcoin value but when you look at their dollar value their dollar value usually stays the same, hence when you look at the dominance sometimes even when bitcoin goes up, dominance stays same. Hence, don't worry about the dominance but focus on seeing greens on the market for couple days in a row, when you see that, that is usually the sign of bull run which will fix this dominance and make all of the coins gain value and not just couple of them.