It's still possible to have different jobs for different projects, just like before, with some kind of build filter in front of them. Those different build jobs can be managed however they are now. This is common. There is no need for a single giant build mechanism that knows all the things.

Packages are a separate concern. And of course you should use versioned packages, just like you always have. Why re-invent a solved problem? Trying to force library upgrades in n-many services all at once, automatically, is a hard problem. Why invent that, too?

Repo consolidation really shines for me in infrastructure and testing - the things that can touch multiple services at once. That's stuff most devs aren't really involved in day-to-day. I think that a lot of the monorepo hatred comes from not understanding other people's problems.