We will still always see the meso civs and eagles, the faster imp arb play for xbow civs, the same knights siege push from the cav civs to deny that, or a kt/camel monk fiesta. Not too much room for unique units unless if the game goes super late. Longswords? if we see them even once I call I will be happy 11
But is this really any different on other maps? Other than Islands or something I can't think of many maps that don't play out like this. You're basically just describing how the best players play the game at the highest level regardless of the situation. We certainly never see Longswords, Arabia or not.
And I'd rather watch that kind of thing on Arabia 5 times in a row than watch the Monk/Light Cav fiesta on Arena even once. Just my take though.