I don't think Beamish has dropped in popularity at all, and might even have increased, as there seems to be a lot of people drinking it, or maybe that's just people I know. I think it's a good alternative to Murphys, because If I wasn't drinking Beamish I would be drinking Guiness. Maybe they will keep it going, and it's possible for a huge brewery to make more than one of a style.
Cheers,
Billy.