The plans for the Reptile House were first noted back at the beginning of 2021:
Not sure if the plans have been updated since then, but the original plans were for the existing Reptile House to close, the reptiles to move to a new-build Reptile House in the Zoo/to other zoos, and for the old Reptile House to be renovated into a museum space. I would guess though that, as a famous part of the Zoo's history, the Harry Potter snake exhibit will probably remain in place (but likely without live inhabitants)
But a new giant tortoise exhibit is planned for this year, in the main court yard by butterflies, you walk through the heated building to view the tortoises, so closer than you do now. And a new reptile house planned for next year, also in the main court yard replacing the show tent. Existing reptile house is no longer serviceable and will become a history of/museum of ZSL.
Not sure if the plans have been updated since then, but the original plans were for the existing Reptile House to close, the reptiles to move to a new-build Reptile House in the Zoo/to other zoos, and for the old Reptile House to be renovated into a museum space. I would guess though that, as a famous part of the Zoo's history, the Harry Potter snake exhibit will probably remain in place (but likely without live inhabitants)