I'm going to make an argument that a lot of people will not like. It's not what I feel should happen, it's what I feel will happen based on other entertainment ventures. WDW is still under-priced compared to other "Premium Priced" entertainment products.
Until the parks start to hit the cost levels of concerts, Broadway shows and big events, it's not going to stop.
Now for the argument for where the precedent is for them to easily drive prices up another 50% or so...
I'm still looking towards the ski industry. I feel they are the benchmark that WDW will head towards. It's the best comparison I can think of for a similar industry that prices themselves towards a premium product: running a similar structure with expensive one day walk ups, multi-day ticketing, AP's and the gamut of very expensive slope side accommodations.
The Epic pass sort of revitalized the AP cost threshold for skiing, most local hills would (and still do) charge well over 1000$ for their own adult lift annual passes. One-day walk up prices to places like Vail and Aspen are now around 160 USD or more. The Epic Pass, while drastically cutting the cost threshold, still costs 899 for the full product and only works for half the year.
You really cannot get a deal on the magnitude of the Magic Your Way ticket pricing in the ski industry. Discounts tend to top out around 30%-40% total despite slapping on as many days as possible. None of these extra days for a few dollars business. Food is probably similarly priced, but totally depends on location.
So based on all of that, WDW is still a much cheaper product. Unfortunately Skiing was a little worse and has had some reprieve by offering products that have actually made it a little cheaper, but they are still ahead of WDW. WDW faces the unfortunate uphill climb to catch up.
All of which is to say I see no real reason the costs will continue to accelerate towards that 150-175$ one day walk-up threshold and the top AP should easily start to hit 1300-1500$ before they've overdone what another industry is already doing. Heck, Anaheim already charges 150$ more for the top tier.