Beware Windows VMs on the rmbp. I use VirtualBox and Windows looks better on non-retina displays, from my experience, as does the Microsoft Remote Desktop Connection (the Mac version of RDP). If you want retina Windows, you can have it via Bootcamp, however, you will need to set the DPI in Windows to 150-200%, which, IMO, doesn't look as good as it does at 100%.
I use Windows VMs for Visio, SyncBack (a file syncing program), and servers (I am a software engineer), so I don't spend a lot of time in Windows directly. However, I have read some posts where people said it's not that different between retina and non-retina for VMs, and I would say it does look different, almost slightly blurry.
If you spend a lot of time in Windows (> 50%), get a Macbook Pro, iMac, or Air, but I wouldn't go retina in that scenario.
In general, you can always wait to switch because something better will always be coming around. When I switched, it was December 2010 and sandy bridge processors were right around the corner, however, I needed it then and I don't regret it at all. Get what you need when you need it.
If I can, I will generally buy around November-December because of Apple's Holiday return policy--you usually only get to January to return, otherwise, its 14 days.