It will work, if we can generate the power and figure out how to build a machine that will actually bend space-time in the manner needed. Raw power (reactor) isn't enough - you have to have the mechanism (nacelles).
I think that's one issue people run into. It may NOT take a whole lot of power, relatively, to deliver the basic effect of warp, and a highly-advanced fusion plant maybe quite sufficient for the pre-TOS era that we're discussing. The mechanism may just require a charge into the material used in the nacelles, and it's the MATERIAL that does the magic.
We're talking really 'pie in the sky' at this point, so arguing definitives seems silly.