SUB-Species aka The MMO player

Speculation has been rampant on just how well Rift: Planes of Telara will sell on release. What even has me more excited is the prospect of a new MMO with a sub class that elevates above most newly released MMO's.

For the last few years, MMO releases went hand in hand with praise (Age of Conan and Warhammer Online), followed by a swift decline of populations due to a buggy and messy affair once players progressed in these fantasy worlds.
Rift has something going for it already, that most do not. An almost flawless delivery of a beta; word of mouth salesmanship; a chance to offer familiar gameplay in a polished and stable environment.
Barring any major nerfage at launch, Rift could contend with the masters of the genre (Lord of The Rings, EvE Online and Aion based on sales and representative data showing higher populations than most MMO's).

This led me to a question of the day after reading several blog posts all stating "Rift will be my MMO along with...(you fill in the blank)"
How often does an MMO player really play two MMO's on a regular basis?
For myself, it always fails. I even tried two years ago. I was subbing to Everquest 2 when I got a "free offer" to return to Age of Conan. AoC had made strides and was playing quite well. I continued my level grind and playtime through EQ2, but felt swayed to log into AoC more each day. Eventaully I felt it just was not worth it to keep both.

Putting this question out to Twitter brought in some interesting responses, and some corroborating data of why the player could or could not continue more than one MMO.

mmosymposium (http://www.mmo-symposium.com/)

 I have EQ2 and LOTRO at the moment as I'm a lifer in the 2nd. I barely have time  for one due to mini me. (EDIT: I assume he speaks of a little one, child in the way)

CedgeDC

yup I bought aoc and war on the same day but didn't touch war till I tired of aoc months later hehe

girl_vs_mmo (http://www.girlvsmmo.com/)

Usually when I would play two MMOs I had friends go back and forth as well. But that's no longer the case.

Scopique (http://levelcapped.com/) 

 I have always run at LEAST two subs at a time. Yeah, it happens. (EDIT: Found out one sub is with his wife)

_Stargrace (http://mmoquests.com/) 

I multi sub - but - that is due to work. If I did not have a job playing video games I would MUCH rather be a one sub gal.

Moxiedoodle (http://www.battlepriestess.com/)

I've been playing two MMOs (WoW & LotRO) for a good while now. But generally one will dominate my time. (EDIT: as I found out, the second sub for this person was LOTRO...as a lifer)

I had many other answers (for example, wargrimnir Grimnir who plays so many games your head would burst, had noted he is a Weekend Warrior Dad...), but a consensus was that it is hard to have TWO or more MMO's.  Some played another game as their wife or friend was in that game. Some would play the other game (or list it) as it was F2P or they were a Lifetime subber.

This had me thinking...where will this leave Rift (or say DC Universe, our latest launched MMO) when the dust clears. What will keep the player in the game and not return to their old sub. No matter how anyone slices it, there is a reason we try to sub to two games..and it is not always because we WANT two games to play.

What do you think the new MMO needs to offer to finally give up your old MMO sub?