I'm in the good/bad position of being married to another Canon shooter. My plan these days is to buy a new camera annually, partly as a write-off and partly so that we don't end up with ancient cameras (two people * two cameras each). Right now, we've got two 1Dx, 5DsR, 5D4, and 5D3 (plus my trusty 1D3 that I refuse to sell). The 5D4 serves as both my wife's primary camera (lighter than a 1Dx, "safer" than a 5DsR as she's not disciplined enough to stay low ISO and shake-free) and a backup to "my" 5DsR. The 1Dxes get hauled out for action (not necessarily for frame rate, but for their responsiveness, and certain other features), and now that we got the 5D4, the 5D3 collects dust (actually it's on loan to my dad with our 100-400) but it is available for when we do Alaska cruises (I roll with three cameras) and when I need a remotely-triggered camera.

However, I'm really torn on what to get next. Do I wait for a new version of the 5DsR, and pay bleeding-edge prices for it? Do I get a 1Dx2 and begin to phase out the 1Dxes (or realistically sell the 5D3 and move the 1Dx to dad's place)? I don't see a need for two 5D4s: if my wife is shooting with two cameras, she's going to want one of them to be a 1Dx for action, and if I'm shooting with two cameras, I'm going to want a 5DsR or a 1Dx long before I want a pair of 5D4s.