For people who are watching Deepwater Black from the SFE feeds, I'm sorry to say that if Sci-Fi Channel stops airing MG, they'll stop airing it on SFE--and if they don't, they'll air it in an obscure timeslot (which is not that much different from where it is now--4:15 in the morning?). As for alternatives, if MG changes networks or goes into syndication in the US, SFE probably won't air DWB either, since SFE's sole source of programming is the Sci-Fi Channel in the States.
However, if it got big enough in the US, Sky 1 may consider it (but we're talking Seinfeld big, since MG is on a cable network). And a relatively new station, called Channel 5, aired Deepwater Black before SFE did, in December '97--they had bought their episodes from YTV, and I'm willing to bet that if new eps are made, Channel 5 would get them.
As for helping to save the show, you might be able to help by writing to the SFE mailing address, which I have not been able to obtain at the moment. Every little bit helps, and if we can convince SFC that it has done well in the foreign market and that they would benefit in that area by reneweing DWB, that would be another point for the 'renew' side.
I have not been able to find a mailing address for SFE, and the SFE e-mail is currently down for reasons unknown. I will try and find this information as soon as possible.