Seeing some significant April schedule changes tonight

Yes. I saw that I received an email with my ticket information for a trip in April and wondered what that was about. Checking my itinerary, 2 changes of flight times - one UAX and one UA.
Neither were overly significant, but strange that I didn't get the notice on the itinerary of a schedule change and asked to accept it. Just automatically changed them both.

Talked to a GS agent abiout this last night. She said that due to the reversal of the policy on schedule changes from the previous administration, changes that no longer trigger either the refund or the change/refund option (small time changes, flight numbers..), since they are now 'you have to accept this change' will no longer trigger schedule change notifications

IAD-GRU not bookable March 24 to April 29
 

It appears that the IAD-GRU flight is not bookable between March 24 to April 29. This is new to me, I am not sure what exactly happened here, nor if the route is even cut during that time period.

There are no other nonstop flights between the 2 cities.

For the first time in forever, a 757-300 is scheduled to fly BOS<>SFO starting in mid-March. I think the last time I saw a -300 in BOS was on an ORD flight a decade ago.

yuck. Yeah, BOS hasn't seen 753s in years, except for last minute 752 swaps.

I wish it was just all 757-200's!

Ditto. But we're back to all 7M9s for the summer schedule. We hope the A321LRs with lie-flats come soon and are put on BOS transcons!

More generally, seems like some domestic summer changes (July/August) loaded last night.

Yeah, weird one for me was the drop of early AM flight CVG->IAD on one of my itins for July. Looks like it is just missing for a couple of days. :(

Are there any regularly scheduled 757-300 routes? Or they just fill in?

I've seen regular routes ORD-DEN and ORD-SFO.

Couple ORD->LAX as well.

sfo-koa
sfo-hnl
lax-hnl
sfo-den
sfo-ord
sfo-iad

Just noticed that IAD->CVG is seeing EMB145s on the schedule. Noticed it when looking at options for a trip in June, not sure when it is starting.
Surprised to see this. It is for a 5PM flight, so not like it is even just for first or last flight of the day.