Life expectancy of LCD/LEDs depends greatly on the type (consumer would die fairly quickly in outdoor scenarios) and I'm sure one could build an LCD/LED display that will last 4 years outdoors. It's hard to deploy such LCD/LED sign (you require power and lots of it to be visible in sunlight) but it's possible.
The important thing here is that this first production outdoor deployment of EPD signs in the world works for for years without any serious problems which confirms that e-paper is a viable technology for outdoor deployments. There was a lot of skepticism back in 2013 if this is at all possible.