You need to check out age requirements for many of these. A full career and retire... Awesome. But cross off special agent. 37 is the limit. Plenty of military members, retired or not, move on to government service in a variety of ways. Just typing this I can think of my friends who work for all parts of the DoD, state department, NCIS (and yes I ask about Gibbs and Abby every time I see them), FEMA, FBI, CIA, USAID, CBP, DEA. If I sit and think about it I can probably name another dozen or so. Some jobs transition more naturally than others. Beltway tours while on active duty can open lots of doors to GS jobs. Plenty of folks on this board have done that it or passed on them for other gigs (I did).
It's great to look ahead but in your scenario this is 25 years away. Military retirement is not a sure thing. Career designation is hit and miss depending on career fields, needs of military, funding, etc. Also at that time you might be married with a herd of children. So many things you don't think about now will come into play.