May has chosen a much better battleground this time out and if she and her party have the stomach to take on the LP then there should be growth potential with young disillusioned Liberals whose party has a significantly less environmental leader and focus compared to the last election. The Greens current low profile isn't that significant, this isn't when people are thinking seriously about their voting options. I just think it's too early to say, although I can see why there would be skepticism that May has the political will to direct her fire in a productive fashion and why the media won't give her as much time.
If May was willing to take on the Liberals then she wouldn't be in SGI, she'd be running in Guelph- where her chances were better and she would have been far more useful as the leader of a national party.
And neither the Greens or May had a low profile before the last election. So barring some big surprise, the expectation is that they will get less in the next election. [Not to mention the effect of even less attention to preparing broadly on the gound, and those other aspects of the organization that have withered.]