It will happen though.I think you mean already followed unless Truss, Kwarteng, Patel, Sunak, Braverman etc was just some horrendous nightmare that we've still yet to wake up from.
The centre right are as far as they've ever been from getting their party back
The only way to win a General Election is really to stick to middle territory, Left or Right.
How long will it take? Well it depends on how successful Keir et al are when they form the next Government, how patient the electorate are with the Labour Government if they need more time to successfully do it their way, and finally, how long it takes for the Conservatives to regather, come to their senses under new blood and re-form as sensible centre rightists. My view is that it will probably take two terms in Opposition for the Tories to succeed in a General Election.