Do you think the Democratic Party will expand over the years?

I hope not.

I hope people walk away and see the Dems as the braindead cult that they are.

It's difficult to predict the answer to your question as the future is always in motion.  If current  trends continue the answer to your question is yes.  If you look at the legislation that Republicans have enacted in the individual states the Republican Party has morphed from being conservative and less government to being a party of White Supremacists.  Republicans can say that they are not a party of White Supremacists but their words and actions say otherwise.  The country is changing and until the Republicans stop trying to turn the clock back their base is going to continue to shrink. The current Republican Party has chosen to neither adapt  to nor to   accept  the changes in the country. 

The moderate Republicans aka RINOS have a choice to make: they can either stay with the current Republican Party or they can form a new party 

Yes, they are firmly united with the exception of the Qpublican Joe Manchin, but he doesn't matter.  Qpublicans will NEVER hold a majority of power ANYWHERE in this country ever again.  trump and his Qtards made sure of that.

It has already we always were the majority of the population ( remember this trump in 2016 was the electoral college president )  look at the clowns / racists / child molesters / liars   in the republican party do you wanna be a part of them.....lol .

Yes, not just expand, it will expand by leaps and bounds. There is no other viable party left. The Republican downfall started with the Tea Party and it went down in flames; lead by the Insurrectionist in Chief. 

Only if we go communist.