Here is one: https://steempeak.com/hf21/@steembasicincome/sbi-in-an-hf21-world-part-1-50-50-rewards
Here is another:
https://busy.org/@steembasicincome/sbi-in-an-hf21-world-part-2-convergent-linear-and-downvote-pools
The impact of 50/50 is negligible and the program will adjust quickly. The impact of convergent linear and downvote pools is impossible to predict because it depends on how people change their behavior.