One thing that needs to be considered if the game goes on steam is the amount of players may explode to well over current arena limits. A game I play the most current called Elite Dangerous is far from the most popular game but it still has 11k-5k active players at any given time on steam ALONE, not counting off steam players. Iv seen it peak over 30k several times. Once AH goes on steam your server might get overwhelmed very quickly if you suddenly find yourself with 30000+ new sign ups.
This is totally illusory. The conditions aren't even remotely comparable between those two games.
Elite had a way older legacy than AH. Old gamers had been waiting for a resurrection for many years. It had big media coverage. A big publicity campaign. A kickstarter campaign which brought 1.5 Million £. A high profile CEO. And so on.
For comparison, AH's twitter announcement about Steam Greenlight has by now been retweeted 4(!) times...
Just putting AH on steam doesn't suddenly give you "30000+ new sign ups"
But IF it really did, I will eat my words and volunteer for extended TA service in the EURO time window (though unofficially, this time).