canberra replacement

any suggestion as to what could replace the UK’s small fleet of PR9s ? I have heard that a bizjet platform along the lines of ASTOR may be considered. But as the likely work is not going to be at Stand Off range the idea of an non-military plane seems a bit odd. Then again I think we should have upgraded Vulcans like the US did with its B-52’s so we still had a long range bomber, so what do I know.