Re: One more step into the dark
the clarity for "movement of [British*] people' is covered by this para-legal draft text, from a recent 119 page document published by either the uk or eu authorities. It's the best guide that we have seen, in public.
In respect of United Kingdom nationals and their family members, the rights provided for by this Part shall not include further free movement to the territory of another Member State, the right of establishment in the territory of another Member State, or the right to provide services on the territory of another Member State or to persons established in other Member States. c.f. Page 23, TITLE IV , OTHER PROVISIONS, Article 32 Scope of rights
from https://ec.europa.eu/commission/sites/beta-political/files/draft_withdrawal_agreement.pdf
personally I will accept whatever outcome Mrs May will negotiate, and I'm not taking sides, but as I currently am exercising my free movement, established in another MS, and would like at some point to be able to mow someone's lawn or mend their PC - it's not looking great, but it's not over until October.
EC is starting to draw up their multi-annual financial programme for after "Horizon 2020", currently codenamed "Framework Programme Nine" it might still contain the UK, contributing their 12% for "close alignment" - or it might contain the ghost of a former member, with radical cuts in many programmes and areas. Only time can tell.
I have protected my situation by obtaining an (optional) "Permanent Right to reside in an EU state" document, which might remain valid after 2020? Unfortunately I can't think of any documents that will help UK Space, or UK academia, or UK Science, industry, basically you are already out of all programmes.
(*) UK is of course free to waffle their own reciprocity ideas on this subject, or perhaps even one day to manage to write something down, I can bring the crayons, no malice intended.