Search, it's gonna be big
The mobile device you have in your pocket or in your hand whilst reading this has, effectively, been around for a long time. I'd suggest for brevity that around 1983 when the Motorola DynaTAC was launched is a good date to pick.
With this, I'd surmise, came a new and/or increasingly used interaction. Pushing buttons with a finger or thumb from one hand whilst holding the device in the other. So for 30 years our muscle memory has been learning and adapting to this interaction so it's essentially become a second nature.
Today there's more mobile phones out there that could possibly be connected to the internet than you can shake a stick at. So the interaction between device, eyes, hands and fingers is used for swiping, tapping screens and the such.
The decrepit navigation bar
Since we started designing sites we included links to pages and other sites. When time moved forward and gave us opportunities to stylise these links we created horizontal and vertical 'nav bars'.
When the mobile device came out and we started going mobile we tailored the navigation for it. We started off making the navigation a long list realising that content was more important to a site visitor we started hiding it or moving it so that the visitor would see the content first with navigation one click/tap/pull/push/interaction away.
Navigation could still possibly be complex. Drop-downs turned into show and hide navigation within show and hide navigation. It seems logical, hiding it away for the visitor to find by drilling down to the link that they need.
But what if we don't need the navigation
Our hands, fingers and thumbs are so used to the tactile interaction of the with a device now that I keep thinking –
"Would asking the user to use a search form element be a better experience for them when visiting our sites?"
A search box which we could coax into auto-suggestting the main navigation when the visitor starts typing 'about' or 'news' for example but allowing them to drill down to the content they need if the wish to.
This way you're not deciding what you think your user needs from your site. You're allowing them to find it and possibly find stuff they weren't aware of.
Possibly possible, it depends
Of course, it depends, but who decided to have a 'main navigation bar' for sections (see chapters) of a website. A methodical way of making groups of 'pages' into something coherent on a fluid web where a visitor would (now) more often than not (I suggest) coming from a search engine.
Perhaps we don't need those 'main' links on some sites. Perhaps we could use 'search' as a better facilitator for narrow viewports (specifically mobile devices) where the interaction (more often than not) would be touching and tapping the glass that's displaying the website.
A possibility dependant.