That timeline is pretty much my guess too.
They do this whole stockpile, develop, sign 2nd contract thing until the big 4 contracts would naturally end after the 2021 season (should they not be moved prior) which coincides with expansion and the CBA ending, and from there they start to evaluate what that process did and did not produce, then they try to either sign or trade for stuff to fill the gaps which probably should get them back into the playoff picture within a year or two after that.
If something too good to pass on comes up in the mean time, I'm sure they will explore that whether it be a signing or trade, yet it seems to me like they are going to sort of set a price/term/clauses, and stick to it with their offers.
The deadlines, the drafts, expansion, their conditional picks still in play, a new CBA, and cap space should make for some opportunities where they could be in an advantageous position throughout all that.