IndieWeb in general and the h-entry and WebMentions specifically.

Collectively they promise a highly personalised web experience that maintains ownership of your own content while encouraging socialisation across platforms, while avoiding the sustainability and scale limitations of activitypub.

I also want to see XMPP/OMEMO have a comeback.

JPEG-XL (someone already mentioned it as .jxl below) image files.

• competitive with AVIF compression levels
• not recycling video compression, so you get benefits like progressive loading
• JPEG transcoding - can take existing JPEG files (so much of the existing images online) and shrink their size by ~20% with literally no change to the presented image, and this is easily reverable. The amount of data this would shrink without risk of altering the data is HUGE.

There are a ton of other benefits but those are the three I’m most excited about.

JXL.