tl;dr: I agree with @chrisse and @Stefan. Make it easy to use F-droid, without forcing people too much.
I have a FP1 with F-droid without anything from google, and would love to keep it this way in the future. I think the open OS should be as open as possible, while being as easy to use as possible… So having F-droid as a system app is probably good, as it allows to uncheck the “unsafe apk”-flag. But I really hate the fact that the ifixit-app on my FP1 is neither updateable nor removeable in F-droid, and constantly triggers the “there are updates available” notification. This should be avoided for F-droid.
Also, it would be nice to prepare some easy way to install an alternative to google location service. I currently use one of the unifiedNLP things with an offline database, which works fine, but I had to invest quite some time to find a solution which works and has a reasonably up-to-date celltower database.