You will not be able to include any mod that the author hasn't given permission for. EVER!!!!
Yes Tekkit ignores this and they have actually admitted that they aren't supposed to do this.
FTB will NEVER do this.
Here's the exert explaining all publicly revealed info on the launcher.
- "You will be able to pick and choose your mods for the packs. All mods can be downloaded individually, instead of just one big zip file.
- It will be easier to add Private Server packs, Just send a mod list and configs. The launcher will do the rest."
From:
http://www.gamrmag.com/exclusive-new-ftb-launcher-and-website-preview/