I get he won a lot of things, but he also bowed out not on a high note and we can't actually say he wouldn't have gone on to podium at best. His peak was around 1980 or so just from the list you rattled off.
You know what else he did? Called his retirement 4 years earlier and fulfilled his prophecy mentally with a drop in performance.
I wouldn't call the 86 Tour a "drop in performance," unless only for not winning it. Yet had he raced differently Hinault could have won that edition, so performance wise he was still fine. Indeed Lemond said Hinault was the strongest he had ever seen him that year. So I don't think a "drop in performance" was the issue, but the motivation to strive to want to dominate as he had in the years you mentioned. His knee problems certainly contributed, but there the situation was technical, riding as he did gears thought necessary in that cycling regime for big power, which put too much stress over time on the connective tissue. Today he wouldn't have had such a problem. The more important consideration I think was that the new crop of talent had by then decidedly arrived and mentally, not physically (because at 32 we know a cyclist under normal circumstances isn't physiologically over the hill), he thought it was time to call it a day. His time had simply come. Had he known Lemond was about to get shot perhaps wouldn't have changed things, because he must have sensed cycling was on the verge of a new age that took off a few years later and so retirement was probably for the best anyway. However physically, with the right motivation, Hinault could arguably have won or at least podiumed another Tour or two, or classic or Worlds.
With Big Mig I think it was a very different story. I believe Indurain was more cooked physically than Hinault at the time of his retirement, because the Spaniard's engine by then was truly in decline. Indeed Miguel knew this by the time he won his fourth Tour, saying he couldn't get any better, but just maintain his top shape, which he did for another year and then it was over. The probable circumstances behind this, which I don't think are comparable to Hinault, can't be discussed here, only that cycling had changed. Whereas Hinault had a career entirely within a certain era, Indurain's spanned two as explained by all the historical documentation and this brought on a sudden physical expiration date.
As for Pogi I think he's just making mischief. He's playing with everyone, journos and competitors alike, because he knows he can keep this up while under contract with UAE, which is till 2030. He's on top of the mountain, bar injury, till then, but his time as king will now each year come closer to the end. Some consolation for those hoping to see light at the end of the tunnel. It's so ironic him talking about retirement under such circumstances, given, that is, the reality of 5 more years at UAE (which must expect continued returns on their investment till then), as to almost be cruel when you think about it.