The next release of calibre, appearing around 2-October, will almost certainly be based on the 'custom field' beta described in
this thread.
One way that you can contribute to the calibre effort is to help test the release. If practical, and especially if you have concerns or an unusual setup, download the beta and try it on a copy of your library. Do the things you normally do, and report if some no longer work the way you expect.
Although we fully expect that the transition will be smooth, people do the same things in different ways. There is no guarantee that your favorite method has been tried by one of the testers.
If you test and have comments, please post them to the
beta thread.