My concern is people building up this double, Giro-Tour double is rare, iirc, only seven riders have managed it. Too lazy to search.
As to a triple...it's never been done simply because asking any rider to have form for 60 plus days over the course of a season isn't doable.
The last one was a ripped off his tits Pantani, was it not?
The double... It's being built up because (a) Pogi is an exceptional rider who has clealy managed his race diary with the double in mind, and (b) the issues attached to the other probable GC contenders.
Maybe Pogi will have a jours (or Tour) sans, Roglic will fall off, Remco will Remco, Vingo will face post-crash struggles - and Simon Yates will win the whole shebang. Or Adam. But I would make Pogi a strong favourite at this point - as do the bookies for that matter.
The triple - I'm being somewhat facetious. But hey, Sepp Kuss rode all three GTs last year, winning the third...
Spoiler
Yeah, I *know* he wasn't riding for GC in any of 'em, but hey.