OnePlus has announced that the invite system for the OnePlus 2 will be much improved compared to before, with much faster invites and a reservation system so you won't have to sit on forums all day to track an invite down.
Source: https://blog.oneplus.net/2015/07/the-oneplus-2-invite-system-new-and-improved/
Source: https://blog.oneplus.net/2015/07/the-oneplus-2-invite-system-new-and-improved/