&gt;M.2 has almost no place in the server market. U.2 does and will for the foreseeable future, but I&#x27;m not sure that it can serve the high-performance segment for long. It&#x27;s not clear whether it will reach the limits on capacity, heat, or link speed first, but all of those limits are clearly much closer than for add-in cards.<p>No argument on m.2 - it&#x27;s a consumer grade technology.  No doubt, someone in the &quot;cloud&quot; space will try it... I mean, if you rely on &quot;ephemeral disk&quot; - well, this is just &quot;ephemeral disk&quot; that goes funny sooner than spinning disk.<p>But the problem remains, If your servers aren&#x27;t disposable, if your servers can&#x27;t just go away at a moment&#x27;s notice, the form factor of add-in cards is going to be a problem for you, unless the add-in cards are massively more reliable than I think they are.  Taking down a whole server to replace a failed disk is a no-go on most non-cloud applications...