They don't necessarily have to reference the comics to keep them as canon. Certainly viewers will expect that the Buffyverse hasn't just been frozen in suspended animation since "Chosen"... a lot of things will have happened and there will be a new status quo. That status quo can be determined by the comics stories, because they represent where Joss wanted the story to go. But since most viewers will not have read the comics, there shouldn't be anything in the show that requires you to know them. It needs to be mentioned and spelled out on screen.
Assuming that the new show is about a new Slayer, the main question that needs to be answered is: are there still thousands of Slayers as per "Chosen", or back to just one? That will presumably be answered by the end of the season 12 comics. The answer, and the circumstances around it, can be recapped in the first episode, and then we can just move on with the story. Kind of like how the events of the Buffy movie were briefly recapped in "Welcome to the Hellmouth" without viewers needing to have seen the movie.
Or if Joss wants to keep the comics canon, before the series starts(if it goes through and is actually greenlit down the line) he could come out with a list saying this is stuff you can't touch or I would prefer you not to touch, this is stuff that I'd prefer you at least hold off on, this stuff is fair game, have at it, and anything else not mentioned I either don't care or if it turns out to be an issue, that's totally my fault for not thinking of it earlier.
With regards to a recap, not necessary, and it may also not be very practical. The tv show was adapted in such a way that it was implied that the events of the movie happened only a few months to a year or so at most before "Welcome to The Hellmouth". This Despite the movie coming out in the summer of 1992 and the tv show in early 1997. The tv show also drastically altered or rearranged a lot of stuff from the movie to fit into the tv show. It should also be pointed out that despite references to the general events of the movie, the tv show rarely went into in depth details. Aside from Buffy and her mom, who I don't think was even formally named in the movie, no other movie characters where ever seen or mentioned in the tv series.
Without necessarily declaring the comics non canon, a new tv show, especially set years or a decade or more down the line could simply choose to ignore them outright, especially if it is felt that the events of the comics aren't going to have bearing on the plot.
