Re: Well, you're leaving
Er, the article does in fact go on to say that the number of EU scientists working in UK universities is increasing, just not at the same high rate it was. Net immigration of Euro-boffin-talent is presently on the up, not down. Future trend reversals cannot be reliably extrapolated from a single new data point, no matter how unwelcome or worrying a development that new stat is. Like everything else BREXITy, it looks like we'll just have to wait and see (alas).
Euro boffins I know of don't want to go home - there's no or little funding for their work in their home countries (which are just as hard up as anywhere else). Quite a lot of them have chosen to get Permanent Leave to Remain sorted out instead of risking being ejected. The UK is a major centre for science funding (e.g. there's a ton of medical charities HQ'd in this country, even the odd tidbit of government funding) that, no matter what, will attract people from all over and will continue to do so.