I really think this would be a better solution than what they have proposed in the roadmap for bonus RP for other nations. Currently I am 100% complete with almost 6 nations in air (just a couple left to unlock from the newest update).
- I dont really have a desire to play ground or naval
- I would like to go through and spade some of my aircraft, but currently I loose 100% of tech tree RP so instead, I just stop playing until there is a new update and work on spading planes while grinding the newest releases.
Even if the rollover was nerfed or rank specific like current researching, i could still go back and spade props and have the research rp go to ground or heli so it didnt disappear. This would for sure keep me playing year round instead of just after new updates.