Facebook community will never grow to the gargantuan megasite that is myspace.
Two reasons:
1) Myspace has everything but the kitchen sink, therefore no one has a need to seek out another means of networking. And pretty much anyone you find on facebook has a myspace account. So who needs it?
2) Myspace is HUGE. It does everything and has everyone. Ergo no one really pays attention to small change competition.
The only time a smaller competitor might rise up to the level of the big boys is if that competitor is offering some key item that the larger institution does not. And in this case, facebook doesn't offer anything that myspace doesn't. Zip. Null. Nada. In fact they offer barely a fraction of what myspace offers.
If these websites cost money, then I could see maybe facebook being able to keep an edge by being far lower in price. But the fact is both services are free. Why would larger numbers of people begin to pay attention to a website that hardly anyone knows about, and which offers fewer services than the one they have already been using? It makes no sense. Pretty much everyone has a myspace account now. And they have their friends lists, comments, bulletins, networking, music, film, comedy, etc...all that fun stuff...what reason would they have for taking the time to set up an account and start adding friends, groups, photos, videos, yada yada to another website that doesn't do anything of what the original website does for them already?
It would be like another phone company springing up and saying, "Hey we offer you fewer features and a smaller network - all for the very same price you pay to your current provider!"
Not exactly something that will be attracting many customers.
I'm not knocking facebook at all. It has its place. But it's simply not anywhere near as useful as myspace, nor will it ever become popular. Their only hope would be if myspace begins charging money for its services. Otherwise, they will remain an insignificant waste of a web address.