'Company-backed' is a very nebulous term. If Microsoft was backing Angular I would have every confidence that it would be supported at least for security fixes

'Company-backed' is a very nebulous term. If Microsoft was backing Angular I would have every confidence that it would be supported at least for security fixes for the next 10 years even if microsoft had to add a whole compatibility layer on there next 3 OSs to do so. Google backing an open source project on the other hand has a whole different level of support expectations in a 3 year timeframe.