Yes, I think it really is cracked. I'm just about to start on the Carretera Austral through Patagonia before starting on the badly corrugated Ruta 40 into Ushuaia. Not a good time to have a cracked frame. Or to put it another way, lucky I noticed it before I got down there.
This is 40,000 miles into the trip, bike has been used hard over some bad roads, but I wouldn't say it's been abused. True, it's carrying a lot of weight and I sometimes go faster than perhaps I should on rough surfaces (considering the load), but suspension has rarely bottomed out - I can think of a few times at the front, can't think of any occasion the rear bottomed. This is with an Ohlins shock.
So what next? I'm not far from Puerto Montt, large port city where there should be competent welders. What sort of welding should be done? What to do to make sure it doesn't f*&%k the electronics (depends on what style of welding is done?). Do I need to drop the swingarm? And if not, am I going to have to worry about heat damage to bearings and seals? (I guess so...)
If it is cracked and you can't do a proper weld without removing the motor...clean it up and weld the best you can, and if there's room, you may want to try to add a gusset until you get to a place where it can be repaired or replaced properly.