do unused racing flats/minimalist shoes have a long shelf life?

I've been running in a pair of streak lt 3s I got off ebay. My experience has been that those shoes are still good. However, the steak lt 1 and 2 have a glued together sole where the glue is the critical failure point in storage. These shoes tend to have the sole come off very quickly now. I have however, not noticed this problem in the streak xc 2-3. The streak xc 2 sole seemed to wear out early (compared to ages ago when they were new, but I'm just going on memory).

In general, the streak lt 3 and 4 are most likely still good and earlier versions are suspect/perhaps better as collector's pieces.

I am not sure if nike continued their practice of using a cheap glue on the streak lt 3 and 4 or not.

I have used every model of these shoes in the past 2 years, but this is all just my anecdotal experience. This is not an expert opinion and I doubt there ever will be one when it comes to buying discontinued shoes off ebay.

The streak lt is a very different shoe than the vaporfly, even if they both could be used for the same purpose. If you are used to high stack shoes or carbon plated shoes, the experience of running in the streak lt is going to be totally alien. The streak lt 3 and 4 are not like any other shoes on the market (well I guess saucony type a comes close kinda) - they have almost a spike like fit and feel.

Lastly, read sizing information available on reviews and letsrun threads for this shoe before you buy them for the first time.

Depends a lot on how they have been stored. Always going to be a risk when shopping on Ebay. Foam should be totally fine, it is the glue that fails as Kvothe mentioned.