do you think other manufacturers like Lucky or even Harmon may make C41 or E6 films in 4x5 and 8x10 sheet sizes?
Currently not, of course.
Harman has apparently stated that it's possible in principle, but no concrete plan or planning exists. This means it won't happen within the foreseeable future.
Lucky is a black box. I wouldn't know what they're working on or planning to do. Their 200-speed color film now appears to be working OK going by the examples we see, so it's technically possible they would transfer it to sheet film format.
Keep in mind that there are basically two ways to go from an existing 120 or 135 roll film to sheet film:
1: translate the product to a different, thicker/sturdier base. This is the 'correct' way as it offers the necessary film flatness and rigidity for further processing the format demands, esp. when going larger than 4x5". However, this involves some R&D to make the emulsion work on the new base material, so there's a lead time and qualification testing involved.
2: just use the same product on the existing base, but cut & box into sheets. This is what's done also by 3rd parties with e.g. Kodak Aerocolor film. It's not ideal, but sort of works OK at least for 4x5" (8x10" will likely be a non-starter). No R&D involved, so it's a "quick & dirty" solution.
