If one follows the MPT approach... a diversified investment portfolio and periodic re-balancing, what is the FA really doing... ok, hand holding.
Even with the personal interaction with Vanguard, I expect it will be hard for the "adviser" to really get to know each client. With the right people skills and a good CRM, they may be able to make it look like do.
Face it, many live advisers use mostly the same portfolio for each person with the same risk tolerance (with a possible shifting for age). Its not like they generate a new portfolio uniquely for each client.
The difference will be the make up each companies portfolios between these robo advisers. I would expect those to converge over time or people may choose their adviser based on past performance if they can get the data.
The area that is left is other financial planning. What $ should be used beyond the robo adviser's reach: rental real estate, MLP(?), tax planning (roth conversions) and so on. I would hope the robo advisers could support the concept of putting the appropriate type of investments in each account type (for tax efficiency). They may not be there yet... and this may require some optimization on the individual level.
“Remember where you came from, where you're going, and why you created this mess you got yourself into in the first place.”
― Richard Bach, Illusions