It might be pay to win, but I am not sure that even a whale would be willing to pay to win in THAT way. Part of the challenge of this game is that even with money, you still have to progress through the research tree and take time to build everything.
Pay to upgrade buildings instantly without saving up the required gold? Pay to place free, current research tree level residences and workshops? That goes beyond pay to win, and into taking the challenge away from the whales. I'm not sure how much this new feature will be used, even though on the face of it it's pay to win. It basically means that after the whales do this they will be sitting at the top with nothing to do, and that... to me, that's boring. Even if I was a whale who could pay for all the culture buildings and diamonds to upgrade my wonders, I would not pay for this.
I mean, there are whales on Khelonaar. They have tons of premium culture buildings, level 5 builder's huts, some even have level 5 Magic Academies. And yet, they obviously don't spend diamonds on everything they could spend diamonds on. I see their buildings upgrading, so they are obviously not spending diamonds to instant upgrade their buildings. This indicates that they enjoy the challenge of waiting for resource bars to fill up, waiting on their builders to finish building before building the next thing. I don't see the people who don't fork over cash to instant complete building upgrades forking over the cash to buy coins and supplies.