This petition is rather futile to be honest. Collaboration itself will unquestioningly continue. However, requesting the UK government to consider full researcher mobility between the UK and the rest of Europe is unrealistic. Migration and "control of borders" has been a major sticking point and likely one for the driving factors behing brexit. Whether you're for or against brexit, you can't escape the political realities behind it. Having mobility of researchers goes against the core of the brexit ideology. Reqesting an exception for research is simply not going to happen.
Källa: