I've always expected a similar price rise too.Nobody knows the pricing.
However the survey that was sent out to ST holders (maybe members too) had suggested levels of attendance. They went from your standard seat, then Bronze/Silver/Gold/Platinum offerings (basically bronze was your usual seat plus access to a 'restricted bar' as I remember, then the silver and up had food packages included and better seats. Gold and Plat also had car parking included)
You also had Tunnel Club, smaller 4 person open boxes (imagine 4 of the posh seats at the cinema in a little pen but in the stand) and then your usual higher end private boxes.
The survey was to gauge pricing. My ST now works out at 27 a game, I expect just a seat will be around 40/45 once we move.
My current ticket works out £486 (£25.50ish p/g) to sit in the Lower Gwladys, which I think is really, really good value for a PL season ticket.
When we move, I suspect I will probably want to sit in a similar style of seat (behind the goal) and if the prices goes to about £750 (£39p/g) I'd be content.
Sadly, any such increase may put may make it unaffordable to some fans because it is close to a 50% increase, but I'm sure that club will consider all that.