True, a paid service is probably more likely to be around in a few years (in general), but does that matter for distributed source control?

I guess if you depend on non-git features, like issues, there's a chance that there's some lock-in. However, most of the ones I use have a migration strategy [0].

[0] http://webapps.stackexchange.com/questions/49729/how-can-i-i...