Message 333911 - Python tracker

I think yes.
People will be notified about depreciation earlier, even after 3.8 release not everybody switches to a new version fast.
For example, I still use 3.6 for my job now (but we are planning to switch to 3.7 in a month or two).
Adding PendingDeprecationWarning to 3.7 is safe, I expect a very few code uses `.isAlive()` on Python 3.