2031 seems extreme when they aren't ending on bad terms and have seemingly let their former member's departure bring them closer but it's all subject to too many variables to even estimate at this point.
Perrie and Leigh have babies and will want to experience motherhood for awhile but these ladies are hustlers so it'll depend on their solo outings success and if they miss being part of the huge Little Mix machine.
I personally do see a reunion in the future and when/if they're back they'll be welcomed with open arms