WWDC is different from a typical conference. The vast majority of viewers for them will be online regardless, so it would make total sense for Apple to optimise for the online audience (and after all, the keynote is basically a piece of marketing), but I don't think that indicates anything for a standard conference.

Personally, as someone who now happily works remote 100% of the time, I would be more inclined to attend a local in-person conference than ever before.