If you're getting a Hub 4, then you should be in a DOCSIS 3.1 enabled area which supports 1 Gbps, but seems VM only "release Gig 1 to Sales" when the whole town/city/district has been upgraded. The only way of finding out is by phoning up and asking.
Be clear on what benefits you expect from going from 500 to 1 gig, because it won't help gaming, won't make any difference to content streaming, but it will make large downloads faster, and there's a pretty modest increase in upload speeds. If you sit looking at "spinning circles" or download/upload progress bars for too long then it can be sound investment, or if you just want it for its own sake then those are good enough reasons, but don't expect the upgrade price to be anything like the deals on offer to new customers. And if you're not reliably hitting your current contract speeds all day, every day, then don't upgrade.
