I haven't heard or read anything suggesting that the 17yo was going to be discontinued, but I can guess/surmise the following:
* The 17yo was vatted from limited stocks, and it also dates back to a period when the distillery was mostly closed. So it is possible that sufficient stock is no longer available.
* I noticed Jim Murray made a point of suggesting that the later batches of 17yo (which he wasn't involved with
) were going downhill, and it might be time to take it off the market. (Whisky Bible, 2004).
Hopefully Gordon/Spirit of Islay can provide some more knowledgable advice?