(Insert about 1000 other examples of very awkward ToS updates)
At which time the company has unilaterally denied my access to something I already paid for without seeking my affirmative consent.
In theory I could stop whatever I'm doing, go email the company a brief to the point letter indicating they've broken their ToS and are unacceptably impairing my ability to use my property under the contract that I did agree to, and giving them an opportunity to amend their problem and give me a rollback path.
Realistically the outcome of this is a brushoff and needing to file a consumer protection complaint or get a lawyer.
If the feature is something like "my car" I can't afford that opportunity cost and am coerced into accepting their contract by the way they presented the amended terms.