NSWESP wrote:Im more worried about a reason for it being out of stock such as a new
model comming out then getting hold of one.
Why is that a concern?
You either want - or even need - the specified lens, or you don't. If you do, you find and buy it. If not, the point is moot.
If you are concerned about a possible replacement, might I respectfully suggest the acquisition of a cave somewhere?
Replacements are always going to be with us, but if we concern ourselves with them then we will miss a hell of a lot of photographic opportunities while we wait for the next replacement. And the next. And the next.
Accept that the supply channel is imperfect, and just get what you need, as and when you need it.