It is my understanding per this Mishna that the reason why we rule like Beis Hillel in the majority of cases is related to the rule of "following the majority". I know there are other reasons given (i.e. Hillel was more humble, which is shown a few times over on Shabbat 31a) but by strict reasoning I believe this would be the rationale. However, it is my understanding that there are some Kabbalistic sources that say that in the days of Moshiach we will follow Beis Shammai. If we are to say that the reason for us following Beis Hillel is by dint of the fact that they were the majority, then this shift doesn't make sense, I can't imagine that when Moshiach comes, Beis Shammai will suddenly outnumber Beis Hillel. I am just wondering how all of the mechanics will work to shift our psak from Beis Hillel to Beis Shammai given that according to my understanding it is the majority rules which will presumably not change upon the coming of Moshiach.