Just as a sanity check: there is no reason (other than your funding agency stopping you) for researches with their own funding to collaborate across borders where and when they see fit.
Btw, here in Switzerland the sky didn't fall either after the people voted to 'leave' (the free EU labor market). After all the doomsday talk, Swiss labs can still apply to EU grants. The only thing that has changed that the money that formerly took a detour to EU now goes directly from the Swiss government to the Swiss labs.
Calm down people. Nothing gets eaten as hot as it gets cooked. Its of mutual benefit for almost everyone in Europe to continue free trade with Britain.