If expertise becomes completely linear, there would never be a reason to use any pve crap ever which is one good thing. This would indirectly result in slightly higher TTK which people do want.
re-doing the expertise curve again is a bad idea imo.
it already has a very very slow approach to diminishing returns anyways. even at 2500 expertise you would not notice heavy diminishing returns.
where is all of this news coming from? i dont see any dev posts in the dev tracker mentioning any upcoming changes in 1.7. yet people are talking about them