I doubt it will really be an issue.  Having everyone healthy and Santana coming back is unlikely to happen.  Here are the likeliest options, in my opinion.

1.  Santana takes longer to come back.

2.  Someone in the rotation gets hurt.

3.  Lance Lynn doesn't build upon his good start.

4.  Romero starts to struggle and gets sent down.

5.  Lynn has another few good starts and becomes trade bait.  If he has another few good starts, his 1 year contract could be a very valuable trade chip, especially with Gonsalves, Mejia and even Slegers down in AAA.

Never worry about having too many good players. Especially with a 162 game season.

When Santana comes back, Lynn could be the long reliever they need.

And what will they do with Trevor May??? Another Long Reliever in the bullpen?? So Lynn, Hughes and May will all be in the Bullpen as Long Relief?

Things change. 6 weeks ago Berrios was the staff ace. Now he is a #3 and someone who has pitched 11 innings is the staff ace. Things change.

Great problem to have. We will have 40 man roster issues this offseason so making some 2 for 1 or 3 for 1 trades might be in our best interest. Of course we wait on trades until the AS break when we find out if this situation is too good to be true, but normally injuries take care of a surplus. Just ask the Mets.

I'd like to see Gonsalves get a few more starts in AAA but yeah, he's looking better.

What about a 6 man rotation?