The problem isn't the cash shoppers, the problem is that even the free players on YUL greatly outmatches any new players, and there are just aren't enough people who are getting to end game on YUL to form their own groups to do astral and endgame with. You are an under geared and an under runed level 51 in a sea of well geared, well runed people that you can't do astral with. A new server 'will' attract the interest of people who feel like they might be able to complete without the years of a head start that people in YUL have. It will attract more interest, meaning more undergeared people to do end game with. The only people still on YUL are the people who are able to dedicated a lot of time, a lot of money, or both.
Yes, you will have a few cash shop people that will just rofl stomp over others. That's always going to happen, but it won't be 11 of the 12 people that you are facing against in WH. When the "P2W" started on Allods, you had a few people that were just ridiculously runed up, you had a large core of people with "average runes" and another large group of people with low runes. They were all able to party up with each other without a problem.
In Yul it's rare to see anyone with below 7's, and if they are below full 7's, it's only just below. The one or two people that come in with 2/3's and are ready to work there way up to 4's,5's,6's and 7's over a long period of time can't. They aren't welcomed in Astral, they can't do anything worthwhile in WH, they are left to grind. New players do not want this. I was one of these people, and I'll flat out say that if I was new to Allods this month and saw the end game situation and where it's at, I'd have left Allods in the dust and have never thought of it again. Just the few months break I took was enough to make me feel like a newbie again without much of a playerbase to participate in. I can't imagine how the people with only level 2 or level 3 runes feel..
Avilon will bring more people into Allods, and that's a good thing for everyone. History will repeat itself. Avilon free players will become just as geared as the free players on YUL, and eventually Avilon will have trouble attracting new players. What to do then? Merge Yul and Avilon, and repeat.
TLDR: Avilon will go the way of Yul, of that I have no doubt. But before it does, it may be able to attract a larger player base to allods, and hold them there. Something that Yul has been having trouble with.
P.S. As for the discussion about the cost and time needed to stay competitive on Allods? I agree. Allods is a game that's an all or nothing in your life. You have to spend a majority of your free time on Allods or you just can't compete. You either end up completely dedicated to the game, or quitting. I quit for 2-3 months and competently regret it, because I'm finding it incredibly difficult to worm my way back in without becoming frustrated at the competition.