If Labour wants to stand athwart the forces of realignment, yelling "stop", they're welcome to it. Virtually no social democratic party did it successfully, and it's unlikely that the trick will work in a FPTP system, which already has a number of anti-Left biases. (1)

The alternative is riding the beast. They can be the party of the squeezed middle, the young at the receiving end of generational inequality and climate change, liberals and ethnic minorities facing an onslaught from the new right, service workers who keep the economy going. (2)

But that requires a pact with LibDems and Greens, and - implicitly - electoral reform. That coalition is likely a 'natural' majority of the votes, but unlikely to ever be a majority for Labour, and even so not necessarily a majority of the seats because of FPTP's urban bias. (3)

Note: I'm perfectly aware that this coincides with my political preferences as well, so obviously I'm biased in considering it also the best strategic solution. And I understand it's still taboo. Labour needs to lose one more time before this is given serious consideration. (4)

Note 2: if Labour really wants to be the party of a shrinking base of retired production workers and council house tenants, it still needs PR and alliances. No party can represent those voters and the rest of the Left's base, and under FPTP no party can win without either. (5)