I've just been looking into this a lot recently and came accross this blog which is good but more importantly has a link to installing a sample with a full implementation...
http://blogs.msdn.com/b/webdev/archive/2014/03/20/test-announcing-rtm-of-asp-net-identity-2-0-0.aspx
Basically you're right, there's been an abstration to allow for a change in type to the key but the email and UserName etc are still there, just at a lower level. If you keep looking at the definitions of what you're inheriting from, you'll find them. I've implemented one with an integer key after coming accross this question...
Here's where they are in Identity 2.0
namespace Microsoft.AspNet.Identity.EntityFramework
{
public class IdentityUser<TKey, TLogin, TRole, TClaim> : IUser<TKey>
where TLogin : Microsoft.AspNet.Identity.EntityFramework.IdentityUserLogin<TKey>
where TRole : Microsoft.AspNet.Identity.EntityFramework.IdentityUserRole<TKey>
where TClaim : Microsoft.AspNet.Identity.EntityFramework.IdentityUserClaim<TKey>
{
// Summary:
// Constructor
public IdentityUser();
// Summary:
// Used to record failures for the purposes of lockout
public virtual int AccessFailedCount { get; set; }
//
// Summary:
// Navigation property for user claims
public virtual ICollection<TClaim> Claims { get; }
//
// Summary:
// Email
public virtual string Email { get; set; }
//
// Summary:
// True if the email is confirmed, default is false
public virtual bool EmailConfirmed { get; set; }
//
// Summary:
// User ID (Primary Key)
public virtual TKey Id { get; set; }
//
// Summary:
// Is lockout enabled for this user
public virtual bool LockoutEnabled { get; set; }
//
// Summary:
// DateTime in UTC when lockout ends, any time in the past is considered not
// locked out.
public virtual DateTime? LockoutEndDateUtc { get; set; }
//
// Summary:
// Navigation property for user logins
public virtual ICollection<TLogin> Logins { get; }
//
// Summary:
// The salted/hashed form of the user password
public virtual string PasswordHash { get; set; }
//
// Summary:
// PhoneNumber for the user
public virtual string PhoneNumber { get; set; }
//
// Summary:
// True if the phone number is confirmed, default is false
public virtual bool PhoneNumberConfirmed { get; set; }
//
// Summary:
// Navigation property for user roles
public virtual ICollection<TRole> Roles { get; }
//
// Summary:
// A random value that should change whenever a users credentials have changed
// (password changed, login removed)
public virtual string SecurityStamp { get; set; }
//
// Summary:
// Is two factor enabled for the user
public virtual bool TwoFactorEnabled { get; set; }
//
// Summary:
// User name
public virtual string UserName { get; set; }
}
}