It's hard to tell bcs there are many options (again, like for interment & smartphones this wasn't the only form of dependency - just what worked the best for the giants to solidify their positions, some didn't name it, and foss lagged in market share).

Also disruptions and monopolies arent about offering something new/more/better, their aim is to get the market share to control the demand too (eg Uber was never to be profitable at first as a market competitor, they dumped capital & underplayed workforce until the taxi companies went out of business then started charging more & paying less bcs monopoly that they essentially bought - that was the plan, no investor dumps money in a company that isn't & won't be making money for a decade, the calculation was future profits).

Random about how AI can become mandatory: maybe a lot or communication platforms could requires AI to function (like Google services require ads). So no AI sub, no access to your chat platform of choice (unless ofc foss, like Signal, Matrix, etc).
A stupid example (at least at the moment) but megacorp apps & OSs (Android/Windows) could for example stop providing simple search (Ctrl+F) options overall unless you have AI bcs "their search is AI powered and they refuse to provide you a less then the best experience" ... so now you have to manually search for a simple key word or pay AI monthly sub (+sell your data & thoughts).
This works bcs most people won't look for alternatives or go open source.

Or maybe services from other companies (AI) will demand to speak to your AI for a simple sign up (no longer email & password and/or mfa).

Maybe there will be AI ring fenced gardens where you will need different subscriptions for services (companies) that only work with one but not the other.

Or again with the smartphones - the big manufactures (+Google) will tie functions with AI subscriptions (eg camera app, settings, desktop customisation, etc.).

We haven't yet seen any mass monetisation, how the payment models would work, how many tiers, how high the prices, etc - but how high the prices can be is determined by how much of necessity it is. And since market entry barriers are high, and megacorps already have their gardens, they will absolutely work on how to shape the environment to make (their) AI a basic necessity.
(It's what shareholders demand, it's what all this money now is for - the investments are so high & the race so fierce that it doesn't make sense unless they can squeeze their users later.)