“they could hire a 50000 man mercenary army from germany and south africa.”
Well, they better hurry.
Otherwise the Shiites will own Mecca. And the entire Sunni culture will be on the verge of extinction.
OR, the big Sunni countries (Pakistan, Egypt and Turkey) will decide to war against Iran...
Can I borrow a cup of popcorn?
If the Houthis gained control of North Yemen, they wouldn't target the Hejaz.
Also, even many Sunnis hate the Saudis for the saudi destruction of Mecca and Medina -- the Sauds destroyed teh tombs of Mohammad's companions and wives and built a toilet on it.
They destroy Sufi dargahs (Sufis are a branch of Sunnis) and smash down on any Sunni school of though that is not their own (the Salafi/Wahabbi school).
There is no one "Sunni" culture - the Wahabbis are quite distinct and quite reviled even among Sunnis in Turkey and Egypt and Pakistan
Also remember that pakistan has a significant Shia minority (many of whom went to fight for Assad) -- and the Baluchis are an Iranian people. They will not risk a war with IRan.