I have to assume that the growth of the TUV is not conducive to courting more moderate unionists who have moved over to the Alliance back into the unionist camp (to the extent that the DUP/UUP are interested in courting them back, though with results like this I would think they have to start trying in a more concerted way to do that).
To their credit, the UUP have made much more of an effort to distinguish themselves from the DUP and TUV this election, though I think that was aimed at turning out unionists who don't normally vote and getting Alliance/SDLP transfers (the latter of which their ground game has made a big deal out of, supposedly). As you say though, it will still require a lot more of an effort in the long-term. The DUP on the other hand haven't made any such effort at all.
The UUP, as I recall, also made that odd deal with the SDLP in 2016/17, so I think they have been after SDLP transfers for a while. Interesting they are still trying with that though, since it has seemingly not done much for them in the past.
What really could the DUP do to appeal to Alliance voters that wouldn't just send its voters to the TUV? On social issues especially, it really is not likely to move towards the center, nor does it seem to want to. Is the hope that eventually people will just come back when the alternative seems to be a border poll or a major step towards one? Seems like a high-risk strategy, especially post-Brexit.
