No it's a fact. Many players from the warband comp scene are playing SP if they play because Multiplayer is no fun.No, you hope so. That's different.
I don't know about NW but I highly doubt it died since there's not gonna be any modding tools on bannerlord for a while.
PK was dead before bannerlord. Now EU has a server again that reaches 100+ players everyday. Mercs mod is still being played.
The qeue times for skirmish get longer now.
Apparently they're working on a single life mode which is cool but if it doesn't have a mmr system or is put into the server list we'll end up with the same problems that we have right now.
Veterans will mostly play against newer players and stomp them. No fun for veterans, no fun for the new people.
Noone is expecting them to abandon SP and only care about MP. But a somewhat working matchmaking should be doable in a week after release (if unlike the entire beta playerbase TW wasn't aware that this will happen).