It also assumes that such removal wouldn't have any effect on longer flights, such as international ones, which are often conducted using the same planes.It is important for your argument to distinguish international and inter-continental flights. I have been on international -- in the sense of crossing a border and landing in a different country -- flights operated on CRJs. But those are short 30- or 45-minute hops from somewhere in the northern US to somewhere in Canada.
The article's example aircraft is the Boeing 737-700, which can be and is used for intra-north-America (Aeromexico flies them to several US destinations, for example) international flights, intra-Europe flights, etc., but is not used for inter-continental flights, which are generally beyond its operating range.
Aside from the anomaly of BA's specially-configured A318s which fly LCY-JFK (and which can't take off fully loaded at LCY due to runway length, necessitating a fuel stop at SNN on the westbound leg), the smallest aircraft regularly operating such flights is the Boeing 757. And even it is limited in the routes it can fly, often requiring fuel stops based on wind and weather conditions; only the actual widebodies have the natural range necessary to do those routes consistently.
Also, when international-configuration aircraft are used domestically in the US, it is almost always a positioning flight for which tickets happen to be sold (i.e., a plane landed at Hub A and needs to operate a flight from Hub B, so will fly that route, or needs to get from a maintenance hub to the hub it will actually depart from for international operations), or a temporary sojourn from base for a seasonal flight (US Airways, for example, occasionally flies its A330s to Orlando to carry Disney visitors, but keeps them close enough to its international base at PHL to get them back when needed). Those aircraft also are configured differently; the biggest difference from a passenger perspective is the existence of genuine business class or even three-class configuration, which is rare on domestic flights -- typically only the ultra-premium routes like JFK-LAX and JFK-SFO are operated domestic three-class.