Just those two should do it. With enough population, Matchmaking would act as a split queue (ie, if its set to sort premades or pug,) while still offering the benefit of filling for partial premades and backfilling for all.
Other than that, you are right. Although I would love for more people to stand up and take responsibility to become more competitive, Cross realm pvp and matchmaking are needed to be less discourage for those whom aren't quite up to par and/or are still learning.
No, quit being stubborn and narrow minded. Proper matchmaking would make it less likely, but not impossible for Pug Vs Premade to happen, it won't alleviate the issue. You don't seem to understand the situation. All it takes is 1 horribly one sided, terribly frustrating game to repel players away, permanently. Split queues are crucial and undeniably necessary for long term success and prosperity of PvP, without it we will lose more and more casual and/or new players that have a horrible first time or common experience in PvP. With Cross Realm, population and queue times would not be an issue. There would be absolutely no reason to not implement 2 separate queues. Your pretense of longer queue times dissipates as the Cross Realm population would be massive. The only benefit to keeping merged queues at that point would be to aggravate the vast majority of your player base with the occasional and possibly common mismatched and unfair match.