We have written about the expected impacts twice.

We will automatically adapt to 50/50 by increasing the total rshares delivered to each member: https://steempeak.com/hf21/@steembasicincome/sbi-in-an-hf21-world-part-1-50-50-rewards

Since the impact of CLRC and downvote pools will be different for every single member, depending on where they are on the curve, we are not making any changes to rshares delivered. https://busy.org/@steembasicincome/sbi-in-an-hf21-world-part-2-convergent-linear-and-downvote-pools

Having SBI support will still help you be higher up the curve than you would be without it.