They've said in the past that being a lone wolf will be doable, I am definitely hoping it will be. While I enjoy being in groups I also like playing by myself from time to time. I think the thing that suggests to me that it won't be TOO hard to play by yourself is the idea of being able to jump in for 20 minutes and still have fun. Usually if you only have 20 minutes you don't have spare time to organize a friend playing with you.