In short, no, an interracial cuckold isn’t the only type but it is however the most advertised type there is by major adult companies.
The reality is there are as many people into interracial cuckolding as there are those into cuckolding or sharing their wife with someone of the same race.
It all really boils down to someone’s personal preference and what turns them on. Naturally if a black woman fantasizes about sleeping with white guys she’ll most likely want to try that whereas if a white woman feels the same about black men, that will be her preference.
In other cases it will be the man who pushes the topic of race in this context due to his own sexual desires. So interracial sex certainly isn’t the focus of the cuckold lifestyle in general but it is a sub-genre of it. It’s truly all in what turns each other on and after all that’s what really matters.
Cuckold Generalization Complex
This question kind of reminds me of the generality placed on guy who are into this fantasy, in the sense that they all want to be part of the cream pie clean-up crew (LOL) but in reality not all men are into that, that’s another sub-genre of the fantasy itself.
So to all the women out there who are just finding about this from their husband or boyfriend, just realize not everything will apply to them as each person is different.