Future of CP Creep

I don't think Niantic thought through the the outcome of making cp the determining factor for gym placement; one could argue that a main objective in the current gameplay is to achieve a maximum gym collect on a daily basis, and in highly competitive areas (e.g. SF) the logical way of achieving this is to solely invest in Pokémon that will teach a high CP, neglecting the 230+ other Pokémon species. And like you said, when a greater proportion of players are able to max their Pokémon, i believe more gyms will consist of strictly dragonite's and tyranitars.

Besides first-come-first-serve, what other ways could Pokémon be ordered in gyms besides cp?

CP is creeping, yes. But this was purposely built as is, it's not too often you see a gym done in this manner because the gym game is controlled by spoofers in major cities and they don't cooperate like that.

Also, this gym is no longer Blue, it's Red now. It was a glass cannon of a setup and a joke if all Dragonites. Some people feel gyms in the inner cities are now stabilizing at 3300, I disagree, I think 3k - 3200 is bottom bitch and stabilizes from there.

Per rural, it's creeping, but 25 - 2800 is still good.

I'm more worried about gyms that never change not because they are so beefy and pumped up, but because nobody is playing the game any more. I put a pokemon in a gym in California during a trip 3 weeks ago, and it was only level 4 at the time. My pokemon has been there ever since.

Would it be walking too much if gym placement was based off a mons level instead of Combat Power? That would surely diversify.

The CP formula needs to change to place less emphasis on the attack stat (with no change to battle mechanics). Also, tearing down a gym needs to be based on the CP of attackers with a hefty "All Clear" bonus independent of CP. (You would have to choose between presteging down or going for the kill.) Lastly, there needs to be an immediate reason to battle beyond just the hope of collecting 10 coins. (Maybe every 100th kill you get a the option for a TM, IV buff, move reroll, free level, chance at a legendary, etc). I don't think CP ordering is the issue; it is almost everything else with the gym system.

Oh well. After the water event most gyms here are so full of Gyarados even Blisseys are having a hard time surviving shaving sessions... And players don't really care if a good electric type can practically solo his way through it, all they want is putting their mons as high as possible.
So yeah, unless Niantic steps in, we will see this SR case happening more and more around the world, and it's only a matter of time to see gyms full of perfect Tyranitars too...