Still offered in 2017, despite the fact that it is not mentioned in Downsview Park's website... nor on their Facebook page!
One of the attractions within Downsview Park, True North Climbing, was kind enough to confirm to me on Decemebr 28, 2015, that the Christmas lights are up again in 2015. I visited Downsview Park in December 2013 and 2014 to ensure they were still offering Christmas light displays. Both times I found approximately 25 displays along the 3-km paved trail running around the central pond: A pleasing one-hour stroll for the whole family.
If you do this activity with another family, it will increase their sense of adventure. Kids will run ahead of the adults, anxious to discover what awaits around each corner (there are lots of turns on this trail). Some diplays are animated. My favourite one was the little rabbit hopping up and down over 15 metres. Make sure you have a look at the displays by the two entrances off Keele.
When driving into Downsview Park from John Drury Drive, off Sheppard Avenue, turn right at the tall Christmas tree onto Canuck AvenueÂÂ (past Carl Hall Drive). I suggest you drive along the round-about you'll see on your right, to admire the first light displays, then continue on Canuck Avenue to reach the parking lot on your left. Walk down the path lined with giant flower pots to reach the circuit.
When you're done, drive eastbound on Carl Hall Road to see more displays. When we visited, there was a fun animated structure representing a soccer player scoring a goal. Check this link to see more photos of the 2013 Christmas lights.