Empirically I think it's demonstrable that there is a big increase in voting volatility.
I would agree that the sort of long, multi-generational party vote has been weakened (for both the CP and LP). But why that indicates the death of the Tory Party I am unsure. If anything it argues that for the likelihood that after a period of time in opposition the CP will be back in government.
I'm still fascinated by what happened in 2019. Tory (westminster) vote completely collapses and then recovers to (almost) 80's levels all around Brexit policy (it seems). Even when they win big, it's a thin win nowadays.
When you say the Tory vote 'collapses' I presume you mean the drop in support they had in polling between Feb 2019 and July 2019?
But that drop in support
(1) was mirrored by a rise in support for the Brexit Party, it shows the Tory vote being potentially squeezed from the right. However if an election had been called it is quite likely those voters would have returned to the CP, as in the end they did. Surely this shows the core support any CP would have
(2) the LP vote showed a similar 'collapse' you might as well argue that that illustrates the weakness Labour vote.
But let us suppose you are right that the Tories are going to collapse. Who are they replaced by?
The LibDems, who even with current problems of the CP are polling < 15%, and have not even managed to return to their pre-coalition levels of support?
Some sort of renewed UKIP? Where is this party to come from considering any lack of base?
It's been an abysmal couple of weeks for the Tories in the polls. But for two years they, a party that has been in government for over a decade, were polling ahead of Labour (during which time some insisted this showed the weakness of the LP vote and how all the progressive would defect to the Greens).
Truss looks like a total incompetent but things are likely to stabilise and when it comes down to it there will be voters that are unhappy but once in that booth will back blue (just as many voters did not ultimately desert Labour in 2010).