Have to disagree with your take on body here.
I went to a residency with a lot of body guys and where we did a lot of body CT/US. Came out thinking I was pretty good at body, and then did a body fellowship just because I liked it. I will tell you I learned way more than I thought I would, and no you definitely don't master body just by being a resident.
Your average resident doesn't get great at body MRI without a fellowship, which is okay as most people don't do that much anyways. That said, if you ARE really good at it, that can be a real asset to your group. Another thing you can get from body with the right fellowship is procedures: this is a great compromise for people that love doing procedures but don't want to go full IR and want to continue doing a lot of diagnostic work.
A lot of what you will get out of a fellowship will depend on the subspecialty interest you show as a resident and what the weaknesses of your residency or holes in your specific knowledge are.
I agree with the general sentiment above that you should do what you enjoy, and pinning down what is "hot" right now is kind of useless, especially for someone not in residency, because you are dealing with a moving target and ever-changing job landscape.
I did almost a year of body fellowship during my fourth year. One of the body fellows left our program and I got 9 months of body mini-fellowship in a row and I was functioning as a fellow. Then later I did a year of MSK fellowship.
There are always new things to learn, but body fellowships are of less added value compared to other fellowships to a group for the following reasons:
1- In pp, 95% of body imaging is CT or US. MRI is not really a big modality in pp. I have seen big groups doing 2-3 body MR a day.
2- In you go to a good program, you should be able to handle 95% of body CT and US cases. And as you go through first years of your pp, you get better. Unless you work in a big cancer center, the pathology is simple; appendicitis, liver mets, .... This is not the case for MSK for example. Most general radiologist can't handle 95% of MSK MRIs.
3- Body procedures are done by IR in many practices. In an average community hospital, IR is not doing PAD work. They also don't do chemoembo or Y-90s. An IR in pp does mostly biopsies and drains and lines. Anyway, CT guided biopsies are not difficult. US guided biopsies need practice and is one of the added values of a body fellowship.
5-
The most important reason: In pp most Orthopods, neurosurgeons and neurologists ask for MSK or Neuroradiologist to read their studies. Otherwise, they will refer their patients to other imaging centers. This is not the case for Body. GI doctors, surgeons, oncologists and internists don't care that much. One of the things that all radiology groups advertise for is subspecialty read on Neuro and MSK MRI. Recently our orthopods asked for MSK radiologist to read even their plain films. I have never seen similar situation for body at least in a large scale.
6- Body is very interesting and is the backbone of radiology. Right or wrong, in pp a body imager is considered a general radiologist who can handle tough cases (tough cases are uncommon in pp, believe me). You will be seen as an experienced general radiologist and not a specialist. My 2 cents.