This is the idea I stumbled upon while writing a post for http://www.gamesas.com/topic/1502347-news-tamriel-rebuilt-a-statement-of-vision/thread.

I love TR team work and always look forward with great anticipation for their new releases. It seems that now TR team are aiming for a more seamless integration of their mod and the original game. But, unfortunately, that won't happen soon. And for now the mainland doesn't feel connected to Vvardenfell at all, so my playing character doesn't have any reason to go and explore all this beautiful landmass. It is possible to travel there but, as I wrote in that thread, it feels forced: it doesn't let me to roleplay. It's not my char who's traveling to other parts of the same province, it's just me - the player - checking out a new huge landmass-adding mod.

So I decided to give players (and myself ) a reason to go to the mainland by moving some quest NPCs to the new landmasses added by TR. I would like to keep this future mod as simple as possible: just moving a NPC, changing a couple of related lines in dialog and updating journal entry, that's all. No major quest changes, no scripting, no illogical, immersion-breaking relocations.

The best candidates for moving to the mainland are, in my opinion, most of targets of Morag Tong writs, and I will start with them.

Ideally I'd prefer to give the player a reason to visit mainland at least once during each major questline.

I'd like to know your suggestions! Which NPCs can be easily moved to the mainland in your opinion? Perhaps, not only NPCs but some artifacts also, if so, then where shall I place them? What do you guys think?

I know you said no major quest changes, but one idea I've come fond of mentioned here in the past has been the need to become Hortator of every house, including Dres and Indoril. Of course, becoming Hortator of Dres and Indoril won't be possible until we have their house capitals available, but becoming Telvanni Hortator could require one to travel to the mainland, since apparently the house-heads are over there, rather than on Vvardenfell.

Anyone know anything about Tamriel Rebuilt and the random map drop-offs?

I really dislike it... you travel to the edge and just fall off into the water. Why not sink the land into the water smoothly?

If you don't know what I'm talking about I can make a video using FRAPS.

That's intended, it's because the land beyond those sudden drop-offs hasn't yet been released. That way they don't have to worry about smoothing out a lot of 'coasts' before making a release.

Could be a nice little tide-me-over, Mr. name-too-complex-wth-does-it-mean?

What about something like moving the Wolverine Hall quest giver (Hrundar or something I think...) to Firewatch? He's already pretty secluded. And doesn't he have the golden egg quest? It'd make even more sense for a mainland-bound client to send the guild off on a wild goose chase like that. In fact, it probably was to begin with if I remember the dialogue correctly.