nek;
Yes, if you start out straight from medical school you have to do a preliminary year in Internal Medicine before radiology. I'm not sure if you'll need this year if you've already completed a family medicine residency, however.
Atleast in the US, radiology is very competitive even though the Match rate was down for the past few years. Radiology programs continue to take only very competitive applicants.
There is some concern in the future re: job security... With the advent of telemedicine many hospitals (particulary in rural areas) have found it cheaper to download images taken in their facility and send them to large tertiary centers for official 'reads' than to staff their own radiology depts with radiologists. If this trend expands to include more hospitals it may mean fewer jobs for radiologists.
Of course, radiologists are needed for invasive tests/procedures. However, there is a turf battle between radiologists and specialists who order the tests. Used to be that cardiac catheterization was a radiologist's job: now cardiologists do these... Same may happen in the future with cerebral angiography, is it the radiologist's job or the neurologist's? The turf battles continue...
Sure, there's always a niche and new procedures to do so the future is open to good radiologists and entrepeneurs...