WotC has stated that they are working on the "first major mechanical expansion" to 5E, so it looks like a break with the regular release cycle. I doubt it will be called "advanced" though, the name AD&D has too much baggage. 5E is arguably more "advanced" than 2E AD&D already, at least if you cound "advancement" by the amount of rules in the PHB.
AD&D is more "advanced" in terms of trying to construct a complete world. Monsters had ecologies, favored terrains, and social organizations instead of just combat stats, for example; there were rules for spell research; there were rules for sprinting faster than a jog; there were rules for diplomacy and negotiaon (reaction rolls); and a number of other advanced scenarios and rules which aren't strictly necessary to run a simple dungeon crawl.
5E often feels like a shallow copy of AD&D. There are enough similarities to be recognizable, but there aren't as many game structures because 5E relies a lot of DM handwaving. That's not necessarily a big deal because I can always just create my own rules, but I don't buy the idea that 5E is at all "advanced" in terms of game mechanics. It might be
bloated with content, but it's not mechanically deep.
It sure would be interesting to have a WotC-supported game structure for something other than dungeon crawling. For example, politicking. You can create your own game structure[1] whereby the players "win" some scenarios by undermining or embarrassing a given enemy whom they're not allowed to simply murder (for legal reasons or otherwise), but you're on your own if you do so, and your subsystem is unlikely to interact well with content created by anyone else. If on the other hand WotC had some published rules module about the effects of "reputation points" and the gaining or undermining thereof, you'd be more likely to see backgrounds/magic items/spells/adventures that interact somehow with the PCs' reputation points, and maybe the Internet metagame would start optimizing for something other than DPR.
[1] Here's a really, really quick version: reputation exists within a certain context which we'll call a peer group. Everyone in the peer group knows the reputation of everyone else in the Peer Group. A minor embarrassment (by the standards of that peer group) such as not getting invited to a party costs you 5 reputation (within that peer group), while a minor victory (getting a famous celebrity to attend) earns you 5 reputation. A major embarrassment (clothes catching on fire at a party) could cost up to half your reputation, while a major victory (saving the city) could double it. (DM's discretion here as to magnitude.) The only mechanical effects of reputation are that you can give it away to someone with less reputation, you can spend it to "attack" the reputation of someone who has less than you do (degrading both equally on a 1:1 basis), and everyone knows how much reputation everyone has. The additional roleplaying consequence is that people who want reputation within a certain peer group are likely to cooperate with those with high reputation, who therefore have the power to enhance or destroy other people's reputations. Toadies and flunkies, in-groups, out-groups, etc., all emerge naturally from this simple set of rules.
You can participate in multiple peer groups and have different reputations within each. I might have loads of street cred (Reputation: 500 among the Waterdeep Toughs) but be virtually unknown amongst the nobility (Reputation: 5 for once attending a certain party) and yet be hated and feared by chromatic dragons (Reputation: 200 for killing three dragons). Note that Reputation doesn't have to mean that people
like you (the dragons hate me), but if I want to spend my credibility mocking a certain chromatic dragon he has to respond (likely by trying to kill me) or be shamed among his peers. A regular peasant wouldn't have that kind of leverage.
