Your proposed future system makes a lot of sense to me. If you're looking to streamline and minimize your streaming chain, that looks like a great way to go.

If you're satisfied with how your current system/amp drives your speakers, then the added ZROCK3 should give you more density, low end, and even midrange goodness.

I have the CXNv2 (modified by MWI) but the CXN100 should perform very similarly (minus the mods of course). They are very good streamers and have a great DAC implementation. I think you would really like the simplification.

I've connected the CXNv2 directly to the UFO25 and it sounds very good that way. I've also connected the v2 to the ZROCK2 before going to the amp and that gives it a little more solid foundation. I currently have it going to the ZBIT -> ZROCK2 -> CSP3 -> UFO25 and it sounds great, but I also like the simplicity of your proposed new chain.  

Since the CXN100 doesn't have any RCA in's, you wouldn't be able to add a TT or CD player for instance, (digital in for a CD transport would work fine). Since you're using it for streaming, I think this would be a very nice setup.

You can always add a preamp in the future if you find that gain riding, tailoring of the sound, or more inputs are needed.

Good luck with what you decide and enjoy the ride!