Upcoming Move Rebalance?

That's about PvP and not gyms/raids (at least that's what I understand reading it). Also for PvP 3-bar moves might be better cause of the shielding mechanic

I don't think so. There are separate mechanics. For PvP will be slightly different, but nothing changes for raids and gyms.

It'll be interesting to see how they implement everything. The article indicates that it takes Torterra longer to power up Solar Beam than Earthquake even though both are traditional 1-bar charge moves. My speculation is that the time/number of fast moves it takes to charge a charge move is potentially going to depend on the move's power and/or its cool down time (Solar Beam has a base power of 180 and a cd of 4.9 seconds, Earthquake has a base power of 120, cd of 3.6 seconds).