I sign just to comment because the comment "(VSphere, 4i) are built on top of the SuSE Linux kernel" is so wrong. The Classic ESX has Service Console is is customized RHEL. ESXi does not have the Service Console. It still does have a command console where one can run ESX commands and a limited set of Unix commands which AFAIK are Busybox's. It also has dropbear sshd.
So coming back to the topic, I too have no idea what VMware is going to do with SuSe Linux.
The Classic ESX has Service Console is is customized RHEL
ESX 3.5 was built on top of RHEL, but vSphere 4 was completely redone. Ask anyone at VMware my friend.
"ESX 3.5 was built on top of RHEL" again far from accurate. The COS has been based on RHEL since the genesis of ESX. Whereas VMkernel is VMware's own creation. At least thats what they claim.
Even if the COS in ESX 4.X is based on SLES instead of RHEL, your point does not still make sense because VMware's future roadmap is to phase out Classic ESX. Sometime in the future, there will be only ESXi.
Not saying that VMware Inc are wrong, but Linux runs VMkernel. VMkernel may them 'subsume' its parent kernel somehow but I'm not sure how they'd accomplish this, nor do VMware like talking about how this is achieved.
There must be more to it though - a couple of hundred million dollars for a Linux kernel which you can have for free anyway would be a steep price, even if we consider it as a talent acquisition to get the engineering team which built that kernel.