This is my thinking, as well. My hope is that Flaherty opts out, but I just don't see it happening, as I think he really likes it in Detroit.
I'm fine with Melton as the #5, but only if we acquire a legit #2. A legit #2 is necessary no matter what else happens with the rotation and is the most important acquisition of the offseason. And yes, I have significant concerns with our offense and feel we need several upgrades there. But without a legit #2, this team isn't going anywhere.
Olson is the only potential #3 on the roster, and with his return from injury, I'll be shocked if he gets 20 starts. So Mize will need to step up for part of the year (otherwise he's a #4). And I do like our depth guys - Urquidy, Montero, SGL - strictly as spot starters or back of the rotation types. We absolutely don't need to sign any #4-#5 starter types. Let's not make the Cobb mistake again.