Several people have asked me whether this makes FediFetcher obsolete. I thought I'd put out a more public response to this question:
Unfortunately I don't think I can retire FediFetcher just yet, as it still has some utility:
Firstly, FediFetcher can fetch context proactively without having to expand posts. (Eg one of my favourite features of FediFetcher is that it pro-actively pulls in replies to posts in my home timeline. I personally wouldn't really want to miss out on this.)
Secondly, FediFetcher can also backfill profiles - something that Mastodon is still unable to do, and, as far as I can tell, has no intention of implementing.
Thirdly, it'll likely still be a while until these changes are available in any released versions, and likely even longer until 3rd party apps have support for it.
I do hope it’s the beginning of the end of FediFetcher, but imo we are not there just yet!
Obviously other users of FediFetcher may have different opinions, and if - once this is released - you personally are happy with Mastodon's built in ‘on demand' context fetch, you should stop using FediFetcher to relieve pressure from your home instance.