In my opinion, the reason for an alt to be created is, and always will be, to fill a need or role the main cannot do. In traditional MMOs, this could have been for crafting purposes, or dual boxing a tank and healer (in my case, a necro and druid). Creating multiple alts to spy, try a different aspect of the game, or to scale up your game play influence (multiboxing miners or bombers in EvE; for example).
So, to answer your question, yes, there are systems being built or in place already to not only enable, but encourage people to have alts. I feel alts will be fairly commonplace as long as the advantages of specialization of characters outweighs being a general jack of all trades over time.
I'm betting the average player will have at least 2 accounts for simultaneous play, with higher intensity players having no less than 4 or 5 for various functions (spying, admin work, crafting, ect)
What I would really like to see is an opinion of Snipehunter or Caspian on how they feel about people multiboxing or having more than one account and their feelings of the impact these types of players will have on their vision for Elyria.