They should get the A220s. the competitive advantage shall supercede brand loyalty. albeit boeing took a major hit to credibility amd quality designing the max for Southwest, A220 will be a better aircraft and can be deployed with more flexibility than the tainted max.
i would expect to see the Boeing SST before anything else new from Boeing at this point. i assume we are forced to only have the 737 Max come out from them until they get over whatever hype they are on with this model of plane.
if your son is allergic to dogs he could wear a mask, sit seperately, or take a different flight. but ada law does not allow the removal of a service animal due to an allergy.