I don't know if Bitcoin dominance is a good gauge though to see how big Bitcoin will be, we have seen Bitcoin like having just 50% dominance but still pushing for new all time high. Plus, some altcoins might be artificially inflating their prices, so it's really hard to look at this data and come up with the conclusion.
Bitcoin dominance must be low to have a bull run. More Bitcoin dominance means Bitcoin is pumping and Altcoins are losing value. But if Bitcoin pumps in value but loses its dominance, that is where Bull Run begins. Altcoins have been bleeding since every correction and it will continue to happen if Bitcoin's dominance continues to increase. The current Bitcoin dominance is 59% which is still too high.
Once altcoins start to pump, Bitcoin dominance goes lower. If we can reach 40% Bitcoin dominance without losing its value, then we will see a pick bull run. For now, the investors are waiting for the US election result. It seems like Investors have some confidence in Trump. Let's see what happens.