I strongly agree with most of your ideas, except that of preventing declined payouts from being burned. @burnpost deliberately burns payouts for a reason, and so do many declined payout posters. Sending Steem to @null decreases inflation, which is good for investors.
An option to send declined payouts to @steemalliance would be great. I already use the benefactor function of Steempeak to provide 25% of my post rewards to several people that I reckon worthy of it, and am confident that all of them would be happy were I to send that to @steemalliance instead.
Thanks!