Every brand that has a large enough following will run into pitchforks for large redesigns - a lot of people are fans for something.
If you want to do this successfully, take a slice from Facebooks playbook. Their site looks nothing like 10 years ago, yet they somehow did all those radical UI changes gradually over years, always one step at a time, (mostly) listening to their user base inbetween.
I remember being really annoyed at one of the changes in about 2008. Looking at the timeline of Facebook, it was probably the rearrangement of the site into tabs (and then into something like the current layout 2 years later). I think that it's telling that I remember being annoyed at the time (and a bunch of other times, after other changes) than I remember what those changes were. Sometimes it's hard to remember exactly what it was like in the early days. So, I went looking and also found a Cnet slideshow illustrating the different looks of the site over the years 
That is false, "running into a pitchfork" is the better, and least likely outcome.
Very often things develop like this: user logs in, can't find the usual button, and abandons the website - a la Mozilla forefox redesign fiasco that halved their userbase in a single month.
Another famous case is Akamai - at around 2013 they had a relatively insignifican't redesign, yet a single button was moved. They did not realize that they quietly bled users for over a year until they got serious and researched the matter. They failed to understand that a double digit portion of their users were non-tech staff like marketing boys who were taught to work in a manner like "move mouse over red rectangle, and push the button"