Verry good question
From what I understand, hardware wise, all PW equipped machines have about the same pumps, tubs, heaters etc.
The one thing I am not sure is if the software of the motor controller can be updated to allow the load sensing required for PW2.0.
If it would be it should be, though that dosen't mean that Miele does it.
But all machines from 2nd gen onwards are PW2.0 anyway, so only a few verry early machines in the first year of production are not in question there anyway.
What I can tell you is that the different iterations of PW2.0 (first iteration only went on Cottons and Easy Care, later Delicates, Shirts and Automatic Plus had been added) are upgraded.
My machine didn't list the Delicates and Shirts cycle in the manual I think, but it used it on those cycles.