Kilimanjaro is almost exactly on the Equator, so there are no distinct summers or winters. You can get snowed upon there in every month, mostly because of its altitude. Yes, the glaciers are disappearing.
I was there one June, and there was a little bit of new snow, although it didn't amount to that much. Depending on your route, the trail can be very rocky in places, and the top of the Coca-Cola Route can be full of loose gravel and sand. Therefore, I think a mid-hiking boot would be an excellent choice, especially if it has an agressive tread.
I had taken a pair of taller boots and some mid-height boots since I didn't really know what the conditions would be like (we ascended the Arrow Glacier through the Western Breach). I wore the mids up to 16,000 feet, and I was thinking of shifting over to the taller boots for the rest of the ascent for warmth, if nothing else. But at the last minute, I stuck with mids, and that worked fine. I did have to kick steps in the snow for the porters, and I doubt that I could have done that with trail runners.