Sooo, I play on Horde-Frostmourne and I have to say I've seen a majority of the population during NA times go down like crazy. Alot of people I know playing classic said they're waiting for TOC phase to return because its more Alt-Friendly than ulduar with gear catchups, i know usually phases are 3 months, and that puts TOC at around 10/15 in about month. WOTLK-Classic releases on the 26th, in my opinion releasing TOC around or before classic hitting would be optimal for population considering 90% of the people I know that have quit are waiting for ulduar to end.
P.S I know alot of people will say "AcTuAlLy UlduAR Is tHE BesT RaID" i know Ulduar is most the mechanically challenging, but alot of people steer away from it and wait for TOC lets be honest.
Lets be honest (lol), they can go and play Lordaeron. There is no reason to do as you suggest. Also, Blizz themselve said they are likely to extend Ulduar + squishes of ToC/ICC gear to keep it more "relevant", so your friends better prepare to farm Uld and get ****ed over with nerfed gear after it