It absolutely would affect them. i'm not speaking about populations, I'm speaking about division of development resources). The fact is they cannot conjure a server out of thin air. Some number of people would have to commit some amount of time to make this happen. It's not something that can be done by just snapping fingers. THere are logistical issues, web issues (setting up the site for world transfers, etc), and hardware issues (installing new server hardware).
This isn't a guaranteed profit proposition. It will cost them money to set up- if not enough people resubscribe because of it, or buy new character slots because of it, etc, it will not outweigh the setup and development costs. SE would certainly need to do a cost-benefit analysis before doing something like this.
Well, I'm happy we have an understanding here.

That's really my main concern. If they devs indicate they can overcome that, then I'm all for it. I won't participate in it, but I don't want to rain all over another person's enjoyment.