I don't think Gmail will be shutting down, Gmail is one of the easiest way to send information and other important articles at ease, Gmail is even used in major companies and other business sites..
I don't see Gmail shutting down anytime soon, except perhaps there's is an issue that need to rectified or maybe there's an upgrade on the site...
Being the easiest or fastest nor biggest is not excusable for a company not to go down or disappoint, that is not tenable because it is not a fact. Gmail may have had a network issue that they are resolving and that is understandable. They have made some solution online for accounts that are having such issue.