Steve Shaw said;
"Evolution does not have a "reverse." Evolution does not have goals and is not a linear process or a progression in any direction. A phenomenon that has produced all the diversity, complexity and beauty of life on Earth is a plethora of Pandora's boxes, hundreds of millions of genies out of hundreds of millions of lamps. The very idea of evolution "going into reverse" is utterly ludicrous."

Correct.

Entropy dictates a slide in one direction, ending with a few slow burning stars getting dimmer and this God character saying "Bugger, that wasn't supposed to happen..."

Reverse evolution may not be possible but if conditions dictate that the appropriate size, shape and mannerisms happen to be indistinguishable from a similar convenient form a few million years previously, it would have the appearance of reverse evolution. The myriad variables you refer to make the probability the same as for any other form.

if it walks like a duck, quacks like a duck...