Finch's construction start date is 2017 so that's a full year before the next municipal or provincial elections
2017 and early 2018 seems to be the magic start date for a lot of transit projects in Ontario. Just off the top of my head: Hurontario LRT, Hamilton B-Line LRT, Finch West LRT, Ottawa Confederation Line Phase II, GO RER (I believe). The mantra is clearly: "Get as many shovels in the ground as possible before someone else can come in and scrap everything."
Projects that have funding from multiple levels of government (ex: Confederation Line Phase II) seem like a safer bet than projects that depend entirely on Provincial funding.
I wouldn't be surprised if we see some movement on Eglinton West before the next election as well.