I am skeptical. There are apps out there extending Gmail's possibilities, already. Look at Streak (http://streak.com), look at Right Inbox (http://rightinbox.com). They are based on Chrome extensions. People use them if they need. The real trouble is Gmail becoming a bulky web app in time. Sending money, now actions in the Inbox. Lots of features, majority will not use. It is unclear, if Gmail will remain an simple email platform (which was the initial idea) or Google's promotion/enforcement ground.
For those who are interested in an alternative service check out Right Inbox. Lets you schedule emails in Gmail, allows tracking emails and setting reminders. http://www.rightinbox.com/
Right Inbox puts a small invisible image in your email. If the recipient’s email client does not particularly block remote images, then tracking takes place. Plus, if you include links in your email, they are also included in tracking. If the recipient clicks a link, then it is notified to you regardless of their email client or so.
Pretty amazing. Excelling in technology and application is not enough to rise up and attract investors. New Relic does a great job deservedly advertising themselves as well.