It has always been notoriously expensive and bureaucratic for a Russian to get a 6 month tourist / visitor visa for the UK ( at least compared to their getting a 3 month Schengen visa - which was always better value and easier for purposes of tourism .... hence why so few Russian tourists want to visit Salisbury etc ) . I don't see the supply of Russian , Moldovan , Belarusian or Kazakh SPs as likely to reduce - on the contrary it might increase over time.
It has however long been much easier for Ukrainians to enter for 6 months , since the visa system was reciprocally abolished thanks to Yushenko , who unilaterally removed visa requirements for Eurovision 2005 .
But I know one or two young Russian women who after having two or three six-monthers into the UK , and hence proving they were abiding by the exit/ entry rules ( rather than coming to work or find a future spouse ) ..........were given two year multi entry visas in the end .
It also occurs to me that the Commoon Travel Area with Eire will remain intact , and so there will always be another route ino the UK via Dublin and across the border , into Stranraer .