Uh yeah. Since the Harkles made it known that they would remain non-working royals, they are not entitled to taxpayer funded security. The new PM could end quickly end his term in office if he and his Govt. decide to give Harry the Met coverage he desires.
RAVEC may state that they will review the issue doesn't mean they're jumping right to it. There are bigger security issues at hand. Harry and Meghan got someone to pay for they're private jet jaunt from Cali. to the UK, rumor has it that it cost six figure. The same person can fork out for their continued private security. I'm sure they're may have to hire some new people, the guys who lived in the US decided not to hike across the Atlantic.