A. "Classic" mode (mostly same as current)
In this mode, kanji and vocabulary schedules proceed separately. This is the same as above.
However, you'll also be able to select "vocab readings only" for your kanji filter. With this system, renshuu will not recommend any readings, no matter how common they are. In other words, if you start a kanji schedule and you have not studied any words with those kanji in them, onyomi/kunyomi questions will be unavailable for those kanji.
Instead, any vocabulary you learn will add their kanji readings into your kanji data, so you *only* learn readings in vocabulary you study. Of course, any readings you manually mark as known will also appear.
B. Vocab -> Kanji mode
In this new mode, a kanji schedule will be attached to one or more vocabulary schedules. You cannot add lists to it yourself, but you can add individual kanji via the + button (like usual).Instead, all kanji that appears in words will automatically get added to your kanji schedule.
So if you studied the word 今日 for the first time, it would add those two kanji into your kanji schedule. The readings that you'd study would be determined by the kanji reading filter mentioned above.
C. Kanji -> Vocab mode
In this new mode, you can make a helper vocab schedule that is attached to your kanji schedule. Consider the kanji schedule as your "main" schedule.
As you learn kanji, a certain number of vocabulary will be added to your vocab schedule automatically. The vocab added will be determined by a number of settings, including (but not limited to)
1. JLPT Level
2. # of words per reading
So for example, your settings may say "add up to 3 words for each reading (again, limited by kanji reading filter), drawn from all JLPT words", or it may say "add 5 most common jlpt words that use this kanji"
(I am particularly interested in what other conditions you'd like to attach to this system)