This is just routine off-season banter. Yes, there are questions about Collins ability to be a starting LFer. We also have alternative answers in the event that he's not.
We'll likely start with Chourio, Mitchell, Frelick and then Collins, Perkins and Bauers as backups.
AAA I would think Luke Adams would get games in LF(maybe RF as he's got a very good arm). He's probably a future 1B, but... likely not 3B with the players we have coming up.
Tyler Black... I know how quickly we like to give up on players, but if something should happen to Bauers, Black doesn't replace him perfectly, but he brings exceptional plate discipline and athleticism to the team.
Lara is an elite Glove in CF who can steal bases and doesn't strike out. He also walks at a healthy rate.
Brandon Lockridge... not at all a fan, but I like to be proven wrong in those types of scenarios.
Collins was good last year. He got fewer chances down the stretch in deference of Bauers who... as you pointed out, was hot and as the Brewers went for more defense with a healthy Perkins.
Any questions about Collins really have to be asked about Durbin. He does not have great bat speed, but he's also a grinder. I have faith in both of them holding their positions until younger more dynamic prospects come along.