Google's desperation to show tracked ads is but one vector in the equation which determines longterm viability for watching Youtube ad-free for free. There are also other vectors to consider like the level of obtrusion required to actually effectively adblock-block, and its related effect on the userbase. And also just the level of inconvenience presented by ads, determined by their length, skippability etc.
The proportion of the userbase blocking ads is still relatively negligible, and this is an outcome manufactured by Google toeing the line between too obtrusive and too ineffective. Any measure I can imagine which would actually capture a significant portion of users blocking ads would also significantly skew the balance in favour of obtrusivity, which they would pay for in lost users.
As long as many users are happy to continue being vigilant in blocking ads, IMO this balance will ensure blocking ads will remain feasible.
In general I would agree, but as it pertains to Youtube adblock blocking - there is no gradual slide into degradation (apart from perhaps to do with the implementation of ads itself, though I'd argue they're less obtrusive now than in their original implementation many years ago).
There is fundamentally no way to adblock-block today which does not involve collecting info in a way that causes obvious privacy concerns. It's not somewhere Google can get to by taking little steps. The adblock-blocking that's been happening to date is easily circumvented. Logically an arms race between adblockers and adblock-blockers will ensue, except in practice it'd be like raising the stakes from a civil war re-enactment to actual nuclear war