@MagicRatAFC stated in Tech issues that he couldn't start a thread on this, so I thought I'd try.
I don't have much to say on it myself, aside from wishing Bruce a quick recovery from whatever it may be and commiserating with those who were ready for the show(s) and especially those who had travelled for them.
No use speculating on what it might be... if it's a temporary ailment, the tour will go on and these shows will either be rescheduled or cancelled (and monies refunded). We could say it's expected for a 73 year old in the (pseudo) post COVID world... which is fair enough, but it's not like this is unique to here and now. Bruce postponed shows back in 1981 due to exhaustion/illness, when he was at his arguable performing and physical peak. Who knows what internet rumoring may have raged back then if it had been around.
Anyway, best wishes for a speedy recovery to the Boss.