How should they get rid of each companion for the sequel?

Easy. All the females are forced to become baby machines, so pregnant and of no use.
All the males are off to buy cigarettes.

Nuke them from orbit. It's the only way to be sure.

Cora starts painting herself blue and quits in a huff when the Initiative refuses to update her personnel files to state she's Asari. She now loiters around Kadara Port, bombarding passers by and anyone(no one) who will listen about her days as an Asari Huntress.

If you want to get rid of Drack replace him with another Krogan. That was something I did miss in ME 3. I never want to go kroganless again.

How about don't get rid of any of them? I'd rather see the same group of characters build over multiple games instead of replacing them with newcomers. Garrus and Tali became fan favorites because they grew substantially over the entire trilogy.

Does it?


No, wait it does.

There are always going to be at least one male human squadmate and one female human squadmate for the purposes of romance. Some players aren't interested in romancing aliens, so BioWare is always going to make that concession.

I think Drack should die for the protagonist's angst, too. Players have already gotten attached to him, and they've set him up as at the end of his days anyways. Besides, they already killed off one paternal figure for Ryder, so they might as well kill off another.

As for the rest, I think they're better off keeping most of them on, especially Vetra. Honestly though, the only squadmates I found interesting were Vetra and Peebee, so I wouldn't mind that much other squadmates have some reason they can't be a squadmate in a hypothetical sequel. Cora could get promoted to a position on the Nexus or helping out the asari pathfinder in some way, for example. Jaal could be doing something for his people. Liam could be... well, I don't have any good reason for him to leave, so he can stay.

It's a tricky situation, because one of the cool things about the OT was being able to follow these characters throughout all 3 games and see their progression in each. In ME2, we got to keep Garrus and Tali in our squad, but we lost the rest. In general, I got the sense that people were fine with Wrex in ME2, but were fairly unsatisfied with how Liara and Ashley/Kaiden were presented and I think this mainly comes down to writing. Wrex felt right. When you saw him it was this triumphant "yeah, that's MY badass friend, step aside" moment. I think a lot of people felt confused and empty after meeting Ashley/Kaiden and Liara. Not saying they should have had the same reaction to Shepard as Wrex did, but I don't think the writing allowed for either party to give enough explanation to each other, whereas you see Wrex and you don't really need an explanation. You get it.

So it's a fine line between having a satisfying exclusion of a character or having a moment that needs to be fixed by DLC (Shadow Broker). However, I do think some characters should return. They have a pretty clear theme of family running through the game. It's not something that was handled perfectly, but there are obvious moments where you see it's something the team was going for (in the PeeBee meeting or Movie Night scenes). It would feel awfully contrived to have all of your squadmates split as soon as ME:A2 starts. If they want to give us an entirely new party, I'd rather get a new protagonist as well. 

I think the issue is that they tend to like mixing up the cast a little each game. I can see a lot of them returning as squadmates, and I can see almost none of them returning as squadmates.

They shouldn't, with the possible exception of Drack.