6 major bus routes, trains every 5 minutes, car park across the road (behind Sainsbury's). A large venue for cinema and cafe. I think it has great potential.
If a cinema chain was interested in opening the first cinema in Lewisham - this would be a great location, even if it is close to the proposed cinema in East Dulwich (but no closer than Brixton to Clapham).
The work necessary to convert the listed cinema building into a multi-screen cinema would be complicated, but I'm sure this has been done with other cinemas in the past, so there will be reasonable precedence to follow.
But the question is whether Weatherspoons is really interested in leaving Forest Hill (or moving to a smaller pub like the Bird in Hand or Windmill - both of which they have managed previously), and whether a cinema chain would be willing to invest in Forest Hill. It would be a massive vote of confidence in Forest Hill if a cinema was to open.