Shane took a risk a few years ago and sold ALL his WWE stock, it was clear he wasn't getting to take over the company ahead of Paul and Steph and he had other interests. He took all his shares out and put them into the PPV company in China - and made a shit load back in a relatively short space of time.
A couple of years back, Steph started shipping Stock and Shane started buying back in - not cut and dried it was HER shares he was buying, but he did start buying back in and it's most likely she was selling to her brother.
Shane has done what his dad did, he went out, put his own livelihood on the line and built something successfully. While Paul and Steph have stayed "in the wrestling bubble", Shane has some pretty sweet contacts outside, he was on the board at one of the major talent/managment agencies for example and it's a pretty safe bet that if WWE wants a presence in China, Shane is gonna be heavily involved as he's the guy they know and do business with - whatever the relative success of that business, being there for 7 years nearly is in itself a big indicator that he is liked there.
Shane is the guy who could have been a legit world champion if we'd never known he was Vince's son - when he did wrestle he was easily as good as many on the roster of that Attitude Era, and why wouldn't he be... all those legends to learn from and rings to learn in growing up.
I always felt it sad that Vince had to "win the Rumble and the title" in 99 when Shane could have made it a lot more interesting, you could have bought Shane v Austin at Mania for the title and while the Austin/Vince tale did drive business, Shane v Austin equally could have.
Apparently he's getting a DVD, which is interesting, be has some classic moments but very few are PG. I can absolutely see him returning to the WWE board in the not too distant future, in another sign that Vince is preparing to hand it over... I think that might be what they've been waiting for, for Shane to be ready so that the BUSINESS side of things is covered, and Trips and Steph handle creative.
He also brings in extra capital - even if YOD isn't doing as well lately, if he sells up he could still realize a good return on top of the $35m he is listed has having (similar to Steph and Hunter combined) so he could add something to the business in that way too.
Not to mention that he is the most popular of the McMahon's with the fans and many of the talents alike.
He's the right guy to take the Vince role as CEO, he's not as exposed as a character - so Wall Street will like that he's not constantly trying to work perception, he has a track record outside WWE that isn't tainted by very much at all (the only bloody eye was Rory McIlroy leaving the agency he's with) and from the "boys" perspective he's been in the trenches... has done all the jobs from referee to selling merch to headlining a PPV and is a guy many of the younger talent now will have grown up watching and perhaps been inspired by.
Shane never HAD to do any of the insane bumps etc, but he did them willingly, gladly and helped make guys like Austin, Taker and the like look better - so they too will have a lot of time for working with him.
From the WWE corporate perspective and Vince, it makes sense to have Shane in that role so he's not handing over to Trips and Steph 100% - Shane has that outside perspective now and that is important. It also takes that "eggs in one basket" feeling with Hunter and Steph... would it be a little harsh on them? Not really, Trips is clearly comfortable in charge of the talent and Steph in charge of TV - neither of them has had much real world boardroom experience - and Shane coming back would let everyone play to their strengths and hopefully grow the business.
As for onscreen - I think if this happens Shane doesn't really become a character again... He might do the odd bit here and there, but not a regular stint. He'd be the perfect guy to finally end "The Authority" for example and give that power to Mark Calloway as the new "President"/authority figure, that's the perfect post Taker role as the onscreen/Jack Tunney type who shows up when a decision is needed - anyone gonna mess with him? No...
Everyone will clamor for one more match - bad idea, I am sure he can get in the shape again and can probably still approximate what he was good at - but it'd be counter-productive, they have Hunter for that and he has been active a lot more recently.
I really do hope Shane comes back as above, it'd give a lot of confidence in WWE's future cos from the outside, it does look like this might have been part of the plan all along.