Agreed.
Clearly, when your three best (or, three of your best four) players are at the stage theirs are at, it's always doubtful, but unless the Thunder take a clear step forward (as opposed to just incremental improvement from some of their young guys), at the very least, they should start next season as at least co-favorites in the West.
Two big decisions loom, however . . .
1) Splitter. I've seen all I need to see the past two playoffs to know that this is not a guy you can "go to war with". I don't care how good a fit he is, zero chance I'd tie up a bare minimum of 4/$32M in him.
2) Backup PG. The days of having Ginobili essentially play this role are over (or at least, they should be) and Joseph is far too limited a player to assume the role.
Unfortunately, I have zero confidence in them addressing these two needs. In fact, I don't think they'll make a significant move period and instead will just hope Leonard and to a lesser extent, Joseph, take a big step forward.