What? I mean...what?
Undertaker had a concussion. Ultimate Warrior had a heart attack. Undertaker wrestled a physically grueling 25 match. Ultimate Warrior was walking in a parking lot. The two have nothing to do with each other.
Why would they have to ramp up their medical screening on cardiac issue because a guy who wasn't wrestling, a guy who wasn't physically capable of wrestling, died of a heart attack? Why would that lead to questions about everyone, or anyone? What questions would that even lead to? And how would that have anything to do with clearing Undertaker, since his problem was a concussion, which obviously has nothing to do with his heart? Why would a doctor even consider Warrior's heart attack and death when clearing Undertaker from his concussion?
What risks is it going to minimize? Ultimate Warrior didn't wrestle, and he was never going to wrestle.. He didn't even run to the ring. So it's not like what he did had anything to do with his death, and they need to change something to stop it from happening again - he would have died even if he was never at the HOF, WM, or Raw. Not to mention, he was clearly at a much higher risk than anybody wrestling for them currently, so there's no risks they need to minimize for anybody else.
As for Undertaker, he had a concussion. Obviously that had nothing to do with his heart, so he was never in any danger of having a heart attack and dying like Warrior did. He had also wrestled a grueling 25 minute match, so it's to be expect that he wouldn't look very good the next day. I bet a lot of wrestlers looked pretty crappy when they were coming out of their hotel on Monday. I bet Undertaker has looked like that after his last five Mania matches, at the very least. Obviously WWE already takes concussions seriously, and they will continue to do so, but concussions have nothing to do with a guy's age so that doesn't change anything for older wrestlers either.
I'm not sure I've ever been this genuinely confused after reading a post. Just extremely weird all around.
As for the OP's question, I think it's clear that Undertaker is done. While you might not like his last match being against Lesnar, obviously Undertaker chose Lesnar to end the streak, just like Flair chose HBK and HBK chose Undertaker, so I don't know why he wouldn't choose him to end his career as well. Especially when you consider the fact that he would've retired at least four years ago if not for the streak. Why would he continue now that the streak is over? You might not want him to go out this way, but clearly that's the way he wanted to go out.
I guess anything is possible, but I'd be very surprised if we saw him again before he gets inducted into the HOF, probably next year.