It could likely be designed to mix arm, efficiency and/or performance cores, all they'd really need to change on the design is the 'control' part to account for the mix of cores.
I know AMD have looked at x86/arm hybrid (I'd guess intel have too) in the past so who knows where they might go now windows can support arm and x86/x64. It could actually work quite well if they could assign 'lesser tasks' to the arm cores etc, especially on a mobile cpu. Samsung seems to be trying to add a radeon gpu to an arm cpu too.
AMD also talked about adding in 'AI' type cores so I'd guess the the modular design had some future proofing in it's conception.
Assuming AMD get the same sort of 'support' from MS as intel did with the scheduler they could completely surprise Intel again with a 'hybrid' design.
At the same time, I'm not sure AMD really needs to go down the efficiency core route, they're not trying to set records for the most power draw like Intel
lol