Pantheon being like first generation mmorpg's will require grouping. Grouping requires good healthy time blocks for each play session. I believe their is a HUGE MARKET for an mmorpg like this. Pantheon will do well if the quality is their. Now that we have the obvious out of the way, I have this to say this:
Social tools..... This may be the single most important aspect for "player longevity".
Three types of players:
1) The fast, have some fun and log out players (solo playgrounds games). Pantheon will not be for them.
2) Hardcore, on all the time players. People with a lot of time on their hands.
3) Large time block players. People that have a life outside gaming, that would love to devote good healthy time when they can.
Just relying on Guilds may not cut it for "large time block players". Guilds expect dependability, at least the good ones.
If Pantheon social structure is built around First generation "hardcore on all the time players", they may loose half the players that would slowly loose interest !!!!..... People that absolutely love the concept, but wouldn't fit in.
Think about it !!..... Many if not most of us can play 4 straight hours starting at 2 pm on Tuesday, or maybe 3 hours "If" the kids go to bed. I'm talking about people that are responsible in life that can't be dependable for game time.
How often do you say "I'm on all the time but don't count on me to be on at 6PM".
Social tools in an mmorpg such as Pantheon need to be well thought out. More so than ever for "player Longevity"
Seems VR is working on this https://www.pantheonmmo.com/content/blogs/151/183/matchmaking-systems-what-we-re-up-to-and-why-part-1
It's snowing like crazy here, I called off work and playing sick
After I snow blow, I'll have a good 4 hour "block of time" to play a game. Will I have this tomorrow?......... definitely not !!!!