The only way they're going to be able to show growth in the long term, is a massive "reset" of the parks business into a premium brand. Significantly raise prices, cover attendance drops with increased revenue, then start to work toward building up attendance again at the higher pricing.
I'm sure they would love to do this, but it's hard to imagine it's feasible. They're not offering premium services (if anything, they're far less premium now than they were 30 years ago despite a higher price tag), and I don't think they can get enough people through the gates, much less sell them enough food and merchandise, at the higher prices to make it work. The parks are built to service the middle class; trying to turn them into an upper class premium brand would essentially require tearing them down and starting over from scratch.
That's all dependent on how high the prices go, of course, but if you're suggesting they start charging $350 a day for a ticket with commensurate increases on merch/food pricing... I don't see how they could attract enough people who could both afford those prices and think the value was there to make it worth it.
I could afford to go to WDW for $350 daily tickets and $50+ mediocre lunches, but why would I want to? There are much better ways to spend that kind of money. Also have to consider that for families it's a price increase that hits repeatedly -- that's not just a $150-200 increase on tickets for one day, it's potentially a $1000 increase for a family of five. They'd be running the risk of pricing out 90% of their customer base.