"Peer review will need to account for code as it does for all reported methods in a paper. "
Peer reviewers of code will have to be paid to do it. This wouldn't be out of line as high impact factor journals already pay some statistical reviewers.
The key limitation with sharing of code as part of methodology, is that nobody has the time to read somebody else's code.
It is easy to say something is mandatory, actually finding the funding to make it possible is the challenge.
It would be nice if peer review accounted for "all reported methods in a paper", let alone looking at code. I would bet a box of donuts that most peer reviewers don't go through the methods with a fine tooth comb. It's just not feasible, timewise.
In my hands, reading a manuscript's methods is the fastest way to reject a paper (all subsections have to pass muster, so finding one that doesn't suffices) on sensible grounds, rather than flashiness, novelty, and other non-sensible criteria.
And if a paper uses newly written software and this can't be found anywhere ("available upon request"), then that's an even easier reject.
Add comment