I don't hold with the idea that you have to vote or shut up about politics forever.
First, I've met enough of the vote-or-shut-up people over the years to know that a significant number will break their own rule. Hands up - how many people voted in the last municipal election? I thought so. Guaranteed that it won't stop the vote-or-shut-up people from talking about municipal politics if it gets sufficiently interesting, despite nobody ever going to vote in municipal elections.
Second, simply speaking your mind with honesty is participating in the democratic process, cliche as it may sound. If you go and vote you have the weight of one vote. If you engage in conversation - even simple griping - you potentially move several votes or even the politicians' own opinions. Yes, the chance may be slight, but so is the chance that your vote will be the deciding vote.
Yes, continuing to support the institutions of democracy is important, and I encourage people to vote on that basis. But if for one reason or another you decide to give it a miss this time around, then by all means feel free to continue ranting about whoever's in power.
Rest assured that I will continue to listen to - or, more likely, to ignore - your views about politics whether you vote or not.
 I've voted in every federal and provincial election since I was 18. Can't recall ever being bothered to research municipal politicans, and I refuse to go and vote if I'm going to vote blindly.