Sorry, typing fast and wasn't clear. I meant Beatrice and Eugenie are like the Kents and the Gloucesters in terms of birth/status but, unlike the Kents and the Gloucesters, they are not working royals. The other difference is that as women, the elder was not going to inherit her father's dukedom and hence there was less obligation on them to be working royals as they are not royal duchesses. Nonetheless, neither was Princess Alexandra, sister of the Duke of Kent, yet she was still a working royal.
Prince Michael of Kent, the younger brother of the Duke of Kent, is not a working royal and never has been, I believe, aside from a few engagments in the Commonwealth. He pursued his own career, first in the army and later a consultancy business. He has many charity interests, however.
Similarly, Prince Richard, the Duke of Gloucester initially trained and practised as an architect. It was only when his older brother, Prince William, died when a small plane he was flying crashed, that Prince Richard took over the duties of the dukedom when his father died and became a working royal.
So, there's definitely precedent for the children of the monarch's younger sons to have a career - it's not a new thing.
Edit to clarify that Prince Michael of Kent's engagements abroad were in the Commonwealth.