So, given that Doctor Who would likely be a better seller, any chance some of the lost stories could receive a similar treatment?

Obviously there's a lot missing, and maybe you'd want to concentrate on a few of the more important serials, at least at first.

If it happened, how do you think it work best?
Film in 16:9 and offer both colour and black and white versions?
Recreate classic costumes only enough to make them passable in HD or stay as close to the original effects as possible?

Only one episode each of these sitcoms is being done as part of a special season to mark 60 years of BBC sitcoms since Hancock.
There's absolutely no chance of missing Who episodes being remade.

Id be happy for bbc 4 to remake one lost story every christmas....

I would imagine the closest you will ever get to that would be a fan made production which I doubt the beeb would ever license (and I was at this point going to link to a version of Nigel Kneale's "The Road" which was done by an amateur company but it appears to have disappeared from t'net)...perhaps back in 2008 or so when NuWho was at its height and with the specials year coming up someone might have sniffed with more interest at the idea but now that it's more of a comfy background part of the tv landscape not a chance I fear.

I asked about this back at the end of March.
It is a nice idea, but as was said then, and now, unfortunately there almost certainly isn't the will (or money) to do it.