No question that Hegseth and RFK Jr are gone and it seems likely that Donald Trump is too but Ds may want to keep him in office to help them in the 2028 elections. 

However, how this plays out will be interesting.

Donald Trump may want to arrange for Hegseth to resign on his own to accept another position, then appoint another person to lead the Department of WAR, while he still has a majority Rs to authorize his new pick.

This strategy could work for RFK Jr, Kash Patel, Mark Wayne Mullin and others on the impeachment list. 

The president has veto power over any bills that the Ds try to pass (unless they can get a bunch of Rs to join them) but NOT on impeachments.

If they vote to impeach and remove with a 2/3rds Senate majority, that person is gone.

Then there's the question of how many and the degree to which Donald Trump abuses his pardoning power to protect everybody the Ds investigate.  So they can't be held accountable for crimes/violations, other than they can still be impeached.