These changes can have some unintended consequences:

For fairness to all users, my feeling is that the CAPCHA should be used to identify and thereby further incentivise carbon based proof of brain upvoting/downvoting.

An option to circumvent the CAPCHA should be available (perhaps in the accounts' settings) yet the rewards generated via non-proof of brain upvotes should be less than if the CAPCHA were used.

With such an approach my feeling is that many of the unintended consequences which you mention would not become issues.

Also, depending on the implementation...

You cover some great brainstorming in the final paragraph.

Again, my thanks for your feedback, @smitop!