What features will 4.0 have that I should wait for?
 

Ok, a 3.x -> 4.x is a *huge* change in version numbers.

So I'm guessing there's going to be a lot of changes that will make a 3.x system incompatible with a 4.x system, especially when it comes to modifications.

I have a LOT of mods running on my vB boards and need to know if these huge changes in 4.0 are worth waiting for (since I'm about to purchase yet another license).

If on the other hand, all the 4.0 changes make my modifications unusable, and the 4.0 changes aren't significant over recent 3.x versions, I'll just buy a 3.8x license now and install all my mods onto that, and stick with it.