So many questions, first of all being WHY?
For varying degrees of time we have been able to train (and retrain) crews with a variety of methods...
Crew training for Gold, Credits, or for naf all, admittedly. Move them to another vehicle and you have the same three options. This, to me, is one of the most-beneficial ways of spending Gold in the game.
On a vehicle by vehicle basis, you have then been able to train a crew with normal grinding. Add to this the option to activate Personal Reserves and take the benefit of various events that have offered crew-training bonus.
Then you can switch crews to Premium vehicles that you have paid for. I have very few Premium vehicles that I have paid for and I don't prioritise their use for crew training, but it is a very important feature.
And then there is Free XP boosting, and some players have probably paid to convert XP in order to boost crew training.
And then there are Crew Books.
Have I missed anything?
Forgetting any special crew members that become instructors- and I have a full Snow Maiden crew somewhere (three on a Swedish TD, I think) and another commanded by Claus (Jpz E 100)- then WTF are WG going to do about that?
The ONLY way to keep the playerbase happy (enough) is to ensure that the amount of XP on any crew member is compensated and that any changes that need to be made to crews are FREE OF CHARGE.
And I still don't get what happens to excess numbers of crew members when the dust settles.
If any changes were required then all that needed to happen was introduce Crew 2 and allow every player one free reset for every crew member to acquire new skills. This sounds like a typical WG complete revamp that only serves to [edited] off the entire playerbase.
Obviously, at this point, they themselves clearly don't have a clue what they are going to do. 