Yes, you will definitely see fewer racers out, since this is the season's downtime, unless you are heading into the indoor track season. Typically what happens in Vancouver, BC is the number of riders at the Burnaby Velodrome Wednesday night training sessions suddenly goes up, and a lot of riders show up for the Friday night training racing. So the young guys are still riding.
I'm still out on the road because it's not that cold yet, and I'm not doing any racing. Although I am thinking about it... my racing age in 2010 is 60, the bottom of the next group, and I've had a couple of years to recover.
As far as the commuter cyclists, there are definitely fewer bikes in the bike room. We (BC government consumer tax auditors) share the room with employees of the Vancouver Public Library, and it is certainly less crowded than in the summer, although there are still quite a few bikes in there by the time I leave. There are a few librarians who are pretty tough, but most are wimps, heh, heh. (There are probably four or five accountants who ride in, but I'm probably the most regular, and usually the only one in the winter, so I guess accountants tend to wimp out, too. But my excuse is that I have an IT background, which accounts for my greater toughness.) The federal government has a bike room across the loading dock area, and it has fewer bikes in there as well.
Luis