Keke Rosberg said dealing with Honda wasn't like dealing with people from another country. It was more like they were from a different world. They do crazy stuff and people don't understand it. Dumping Red Bull makes no sense to us, but it does to them. It's a cultural thing.
I may miss one here, but Honda pulled out in 1968 or so (Jo Slessler's death was probably the last straw) and then won two championships with Williams who were then summarily dumped for McLaren who won four championship and then Honda pulled out completely. Both Mclaren and Williams were screwed for several years until they could get another works deal.
Then they came back, ran a few years and sold the team to Brawn, that eventually became Mercedes. Honda has been in/out, in/out for at least 50 years. It's not a surprise they left Red Bull, but I am surprised they came back so quickly. Red Bull had Honda branding on the cars the last two Japanese GPs, and while they were not completely out it did not look like they would continue until we saw the Aston announcement. I'm probably not the only person that was caught by surprise.
They won't be able to dump Aston quite so easily because the pattern is well known, and I am sure Lawrence is smart enough to lock them in solidly under contract. Sure, Honda had outs in previous contracts, but Stroll probably doesn't play that way. Stroll is going after all the big guns and with both Honda and Alonso he's going to have the right pieces to challenge for a championship.