When Bitcoin market dominance start coming down then altcoins will start their up move. It is very difficult for altcoins to rise till the dominance of bitcoin will not start dropping or stay at any level.
More simply, bitcoin dominance is not a good thing for altcoin because of the energy source that gives bitcoin more dominance and power over time, all generated from altcoin, whenever the dominance of Bitcoin achieve at high levels, altcoin always going down and losing the green season. But besides, it's not good for altcoin but it's good for us when the value of bitcoin increases, we hold more bitcoin will be a good thing, almost all of us have certain expectations on bitcoin, so hopefully bitcoin dominance should be reasonable, it should still create conditions for altcoin to be balanced, everyone will be happy.