Boeing are within their rights to flag a potential risk from anywhere in the aerospace industry, however, whilst aimed at Airbus, it's more likely the real intent was to make EASA aware that the rest of the industry is watching.
321XLR is an excellent piece of kit, it's a (well) proven and respected design, with some relatively uneventful upgrades it's still a top tier performer and giving it the extra range makes it very desirable with longer, thinner routes becoming the new norm..
I have no doubts that it will gain EASA approval, whether in the proposed format or in an EASA specified format.