I'm sure he can update his software and systems but what about the thousands of other programs and billions of other machines.

Well, empirically, we can see what we have now is that the software on billions of machines have been updated, but the transition has not completed. You have to eventually get there one way or another for the full transition, regardless of your transition methodology.

So, yes it may very well have been "easier" (as in shorter timeline) in the long term to accomplish the full transition under djb proposal.