Saudi Arabia and Katar are financing and supporting them..They probably didn't count on Russian systems and intervention.
Most likely they will hire mercenaries. Saudi Army does not have balls.
That is what they are doing in Yemen. They have hired thousands of mercenaries from all over the world, with soldiers being shipped in from Sudan, Colombia, Pakistan, Gambia, and Comoros. Local media is claiming that the Blackwater guys have been hired to give training to these mercenaries. But still, the Houthis are kicking their ass.