Labour really has two paths now:
1. “Old” Labour
Have a leader more moderate and popular than Corbyn, and move the party in a populist, economically left direction while deemphasizing culture and social issues in order to appeal to cultural conservatives. Essentially, return to its Old Labour roots.
Pros: Potentially more easy electorally, can grab back marginal North seats.
Cons: Feasibly unlikely now against Johnson’s Tories and post-Brexit world.
2. “Remain” Labour
Fully embrace the Remain coalition of cosmopolitan, socially liberal and market liberal middle class; co-opt Lib Dem’s coalition, while maintaining social democratic policies and emphasis on economics. Similar to Blair’s New Labour, but without the neoliberalism and Iraq-baggage.
Pros: More feasible electoral future, seal in place the new Brexit political divide. Potential to unite the left by taking Lib Dem and Green votes.
Cons: Electorally fraught, difficult to break through with Lib Dem Remainers in the South; hard to win Conservative southern seats.
If I was Labour leader, I’d pick option 2, but that’s just me.
There's not enough woke London suburbia and university towns to make option 2 a road to an electoral majority. At least not with a FPTP electoral system.
To illustrate the conundrum of that potential strategy, despite the fact that the popular vote in the referendum was close in 2016, it's estimated that 406 constituencies voted to leave in while 242 voted to remain.
Option #2 is probably more likely, if for no other reason than they've won three majorities with that formula and zero (in the last forty-five years) with the other one.
Blair managed to win those majorities by bringing in new metropolitan middle-class voters to the party while simultaneously keeping the traditional working-class base in the North and Midlands loyal. Labour needs both groups to be successful. Remove one and the floor falls through, as it did last week.
Still, you are correct that strategy 2 is more likely (with the exception of New Labour's centrist economics which are not coming back...), but it hasn't much to do with which strategy that would actually be most successful. The fact is that most Labour members today are metropolitan types and they'll choose a leadership that speaks to their own preferences, not what is actually going to win elections.