What'll happen to my ripped 320's?

So I have a pretty large library of 320 kbps mp3s ripped from my huge collection of CD's going back 25 years. If I subscribe to Match, what happens to those files? Do they get scanned and erased (from both my Macbook and iPhone?) and only made available again via download (not talking about streaming, just downloads) from iTunes as 256 AAC?

I spent years ripping my collection at 320 kbps, and one of the marketing gimmicks of Match is that everybody's crappy mp3's will get "upscaled" to 256 AAC. Thanks, but I'd rather keep the 320's I already have. I actually prefer to purchase new music on CD and rip to 320. Believe it or not, CDs these days are cheaper than downloads and you can rip to any format you like.

So, what happens here?

Bonus question(s): How does this factor into the "iCloud Music Library" (still not entirely sure what that is) and iTunes Music?

Thanks!