Here at Gamereactor we write esports with a lower case 's', and now Wikipedia has waded into this debate by deciding to do the same, rather than spell it as 'eSports', following in the footsteps of other outlets like Dot Esports, ESPN, and Associated Press.
"So, to be clear, there is no mandate to change "e-sports" to "esports", and it should only be changed on a case by case basis, with a good reason or a local consensus [...] On the contrary, there is a unanimous consensus that the use of "eSports" is not reflected in reliable sources and thus is not correct and should not be used," Wikipedia writes.
Now we're not saying that Wikipedia is the deciding voice in this debate, but it's a big body with a lot of influence, and seems to have reignited the discussion about the format, with the hyphen in the middle still being acceptable. That said, spelling it as 'eSports' isn't necessarily wrong, but is moving away from a growing trend to spell it as 'esports'.