If we get a couple hundred a week playing the game may get back into the Major Nelson top 10 original xbox games played each week. Last time the ranks reset they went up to about 60-70 so that's how many played that week. Like Zombie says, if there are a few regular day/times people get online soon everyone will know and it will get busy.
This is the page to keep an eye on -
http://games.ea.com/information.jsp This is where they announce the upcoming servers being shut down.
They added close dates from the past couple of years of Sept 07, Nov 07 and July 08 (81 closures in 10 months!)
Then a gap and 16 closures announced for Apriil 09. Nothing since then, so an update could appear imminenetly.
Or maybe the cost of keeping the servers up has become so minimal that they are covering costs easily by the continued sales of games more than 12 months old. I know for a fact people still buy B3 on the marketplace (where available) so why stop selling it? Especially since they have a suite of Burnout games on there.
That being said, I'd advise anyone wanting Burnout 3 NOT to buy it on the marketplace but to buy a second-hand physical copy off e-bay or from a local store.