Integration and one-stop availability is the right direction.
The question is, will they patrol the content and remove certain mods? If so, Nexus might be the only place to get ALL mod releases.
Example mods that may be removed -
- Killable children
- Marriage nvde packs
- sixy clothing packs
- Jiggly briasts
etc.
Hopefully they won't remove any mods whatsoever, as it's a 16-rated game anyways, installing mature mods is the user's doing, therefore they should add an 18+ FLAG, but not entirely remove content.
On the other hand about the nexus vs. steam workshop thing, Nexus is run by unprofessional asswads, not caring at all about their customers. And if anything it's a step forward to add a function like GMod's toybox, 1-click addon-download at its best. This has also been more or less added into WoW by the Curse people, by creating the Curse Client, which lets you access a mod database through a program, allowing extended filtering and control.