It is usually bad news for an army when its center collapses. In commercial terms a giant gap in your product lineup appears and people in that segment buy from the competitor because you have no offerings.
The Democratic party can still survive and even prosper but at the risk of becoming a niche player, no longer a full service political provider. It can come to power by allying with a centrist power as some European Green/Left parties do.
How to do this coalition govt in a presidential system, not a parliamentary one, is going to be a problem.
