Im not sure Labour is left, this one is certainly centre right, especially on immigration, fiscal responsibilies, business, law and order etc... i think the last time we saw genuine centre left labour government was the 90s, despite Corbyds efforts.
I dont think theres anywhere for Labour supporters to go, Tories might have some of the middle return, Reform might take a tiny few, Plaid and SNP will get the nationalists, butni dont think LibDems or Greens take many either, too many of theor progressive policies are drowned out by the stupidity.
I think Labours biggest issue is relevancy, they spent so much time on the sidelines, Corbyn got close before they benefited from a Tory collapse, Labour hadnt been in power for so long people forgot how inept, and dangerous they also were.
I think someone mentioned it weeks ago, we are headed into a rebelious voting era, where Labours big threat is from a weaponised public looking to punish them, like the Race to 0 campaign the Tories just endured, i think thats why we are constantly seeing Starmer U turn on issues, i think hes read the room, and now wants to just fade into the background on every issue, as hes doing with Trump.