They will simply just find that people stop using youtube if they block you from using adblockers. Its fairly simple. If you want ads, make them unobtrusive and rare otherwise we get pissed off and block them.
I don't watch any ads anymore and I personally boycott buying things that are forcefully advertised to me. Maybe ill start contacting companies that have "unskippable and unblockable" ads and telling them that I will never buy their product because of how it is being advertised and will make a point of telling others not to either. Maybe even start maintaining an online list of companies to not buy from.
I see maybe 2 or 3 ads per week with my current setup. Most of the time a browser cache clearout fixes most problems. After the 1st jewgle tried to make kiketube unusable with blockers but it didn't last long with people posting workarounds.