Looks like China Airline is still flying that route as CI120 (
0815-1045) which is very likely what you’ll be rebooked to. If you prefer to cancel you’ll also be entitled to a full refund with no penalty. I’d suggest wait till Monday and call either the 1800 number, or their SFO direct number to get a confirmation. If you have another routing in mind (ie via HND), you can ask them as well and see if they can accommodate. The bottom line is you should not, and are not expected to pay out of pocket to fly tpe-oka as it’s the airline’s responsibility to fly you to your destination within a reasonable time per the ticket you purchased.
P.S. Yes BR will rebook you to their rival if they see fit. Had the pleasure of flying a CI 747 to HKG when my inbound flight from YYZ was late.