If I were still based in London I wouldn't change because of these changes. I moved to Singapore 3 years ago (with some continued travel to UK, some business travel to US and some regional Y travel). I have duly been maintaining my BA Gold status, but have also started building SQ KF.
I will probably switch fully to SQ KF now, status will make my regional Y travel better and redemption availability to London is good, and now redemption rates are more attractive than BA.
I will miss BA, but to get over it am just looking forward to my first redemption in Suites SIN-LON next month