Last year Quickstep, Trek, DSM, Jumbo, and Lotto rode (and Qhubeka, but let's stick to teams that exist...)
Sidenote: even with 8 WT teams, they could theoretically still make a national team of only WT riders. I don't think they will, though.
I only mentioned other teams than those Velolover2 had already listed.
I also doubt the national team will bemade up of only WT riders. Some of them will presumably be riding the Vuelta instead.