A simulcast would be kind of cool. I could see them trying for that when the series officially premiers. I'm not sure they could show the preview that will air along with the re-release of the anniversary movie.
Well, the classic Yu-Gi-Oh! ratings tend to be around 1.0 and are consistently better than what 5D's gets, although there could be factors like the different times they air and what else is playing when 5D's is one that contribute to that. I wouldn't mind them taking a risk like that with pulling it off the lineup for something new, but the problem is that they don't really have anything ready to takes its place at the moment and until they get something off the ground, possibly something like that Tai-Chi Chasers show, I don't think that they'll get rid of it. As far as I know, the 5D's merchandise seems to be doing well, or at least the card sales are. The only market that the classic Yu-Gi-Oh! could fit into would be all of those re-releases of the original cast's cards and that Marik Structure deck.
While 4Kids doesn't have a great financial position right now, I certainly wouldn't say that they have no money. Otherwise they would have filed for bankruptcy already and be unable to continue dubbing 5D's. I think it's more of a matter of being unable to find toyetic shows that could work for them more than not taking risks.