I understand the sentiment and I don't want to be completely dismissive but this is a lot.
A casual hardcore player as myself would be able to be ready for the ultimate playing casually in a static or savage, it will definitely take more than 8 weeks but I can do it at my own pace without having to take PTO.
I personally think that telling 2 months in advance is fine, well at least for my job it gives me plenty of time to apply for PTO if I wanted to go world first / hardcore.
The 3 issues I see in your situation are more related to your own goals and choice.
1- Wanting to clear fast (8 weeks)
2- Wanting to have multiple classes geared
3- The lack of motivation to clear savage if an ultimate is not released after.
These 3 issues could be fixed with 2 solutions to be fair:
1-Unlock the tier faster if an ultimate is announced, giving time to either start a savage tier later without being penalized and/or gear more jobs
2-Fix the gearing system with options such as unlocking the alternative ways to get gear faster such as hunts, alliance raids, criterion dungeon, etc. and maybe add more of them. Other options would be welcome too but I can't come up with anything else at the moment. ><