EVS - Electronic View System.
Congratulations - you just named almost every modern digital camera! They almost all feature an Electronic View System, and having Electronic or Live View display doesn't preclude an OVF. In fact, DSLRs have Live View, which nobody is really going to be want to differentiate from 'Electronic' View.
SYSTEM does not, IMO, denote an interchangeable lens camera when used in conjunction with Electronic View. It appears to read 'System that uses Electronic View'. IL is the only way to denote interchangeable lenses until someone comes out with a new word that means the same thing. Until then, SYSTEM is really just too broad a term unless used in a term such as 'Camera System' or similar.
IL is not something you can just toss out, same with Mirrorless. They're too ingrained and widely used to dismiss at this point, whether you like the approach or not (agitated folks bleating about how you 'can't advertise a lack of something' seem to overlook how it worked fine for TUBELESS tires, CORDLESS phones, WIRELESS internet devices and myriad other products).
EV is currently most often used for EXPOSURE VALUE in camera lingo, not ELECTRONIC VIEW, so yeah, that's going to have to be out, as well. Sorry, but it's a very well established acronym: http://www.ehow.com/about_5465537_camera-ev.html ...Now, if you want to use EVF, that's another story.
I see what you're trying to do, but 'EVS' just doesn't work, if for no other reason than it fails to identify either the large sensor or lack of mirror, the primary traits that differentiate these cameras from compacts and DSLRs. At least MILC clearly defines Micro Four Thirds and APS products like the NX and NEX, only leaving the X1 and X100 to fend for themselves.