I've been working on a late copper age, early bronze age setting for a while now, so I decided to use that for the first DFRPG campaign. So far it is the easiest time I've ever had taking a system from the time period it was written for and moving it to a different time period. At some point, I would love to see how it handles in a far-flung future setting.
The current campaign is soon going to be focusing around Deities and the struggles between them, so I'm going to be supplementing a lot of the "Plot Device" level beings in DFRPG with stuff from the In Nomine setting. Its focus around story telling should make transition to DFRPG fairly easy.
I'm also planning to port a lot of the original World of Darkness setting into the later parts of my campaign. I especially want to increase the variety of vampires by breaking them up into clans where appropriate and introducing new vampires where they don't fit the Dresdenverse courts. I personally don't foresee any problems with these ports either as when you get down to it, both systems are Skill vs. Difficulty based, the difference just being how the result to compare to the difficulty is calculated.
I'm not doing it now, but at some point in the future I'm sure I'll run a game in the AD&D Forgotten Realms/Spelljammer setting.