So Trump is impeached then Pence becomes president. Isn't that worse ?
A resignation/impeachment goes beyond scandal. Its an historic disgrace for the country, and if Pence were to replace Trump his administration would operate with little executive agency or political capital. He'd simply be a lame duck, biding time, until the next admin (democratic) assumes power. Pence would have zero chance at re-election.
But to answer your earlier question this scandal, in my eyes, isnt a knockout blow simply because republicans control congress. The house intel and oversight committees are already circling the wagons and supporting administration talking points because their loyalty is to trump, not the constitution.
But how long will this party-wide loyalty continue?
Republicans in the house, especially, have their own political futures to think about. Especially in the 2018 midterms. Trump had zero goodwill or cushion from the public with historically low approval ratings out the gate. If public support continues to erode republican rats will start to jump ship and distance themselves from this toxic and incompetent admin thru their votes and rhetoric, which will completely undermine Trump. The impending civil war is when the real fun begins.
I love my sports metaphors. Think of the Trump admin as a boxer thats getting pummeled against the ropes. Thats what makes his attack on the fourth estate so suicidal. Instead of playing nice he went the Nixon route, and turned them into the enemy. Now you have agencies like CNN and much of the media who are making it their mission to take Trump down. Bannon overestimated his intelligence, and got drunk off power like nixon. The hangover is coming.