Yep, if a player gets the best protective magical items in the game, and take the right class options and spells, they have a really high Armour Class and are hard to hit - same as it ever was.
(Off topic 1: I recall from one edition the write up of Grazzt was that he could hit any Armour Class on a natural roll of 13 or higher, I thought it was a cool ability to get past the uber munchkin AC fiends)
( off topic 2: GWL - what do you consider are the most crucial elements of 4e style play ( or any other edition) that are not replicated, or able to be replicated in 5e? - I don't know 4e well but for mine:
1. unlike in in 1-3e a high level character is not able to wade through an army of goblins or orcs with impunity ( I guess unless you are that uber high AC guy?) and;
2. that unlike 3e the best way to defeat the BBG threatening your city is not necessarily to wander off into the nearby caves, kill a bunch of stuff, level up 5 times gain a heap of enhancement stuff, then come back a fortnight later and crush it.
.....but I think that these are good things)
As for the list of info from the DMG it is too scarce to influence me one way or the other - but the PHB and MM have been enough to make me look forward to the DMG.