iTunes Match and Library on NAS
It will not be able to automatically switch. What you'll have to do is create a new iTunes library that is used for streaming only. To do this, open iTunes while holding the Option key. Then selected "Create new library" and name it something different, I used "iTunes Streaming". Then, simply turn on iTunes Match and you'll see all your playlists populate. Once you do this, you'll be able to stream all your music directly from Apple. When you're back home, open iTunes again while holding the Option key and select your original library.