While some of the points he raised are true (such as the fact that the game is outdated in certain aspects like the gameplay,gear,tomestones,etc,...),
I really don't think adding difficult content would be a savior for the game,
on the contrary, maybe it will be the case for those who enjoy this type of content, but it's quite obvious that the participation rate in savage raids is negligible, not to mention the ultimate ones.

So, I'm not sure if this solution is effective, either in the short or long term.

No, they should add innovative PvE content that is neither too easy nor too difficult, making it accessible to everyone and providing sufficient engagement,
and I'm not necessarily referring only to exploration area.