Really clever thread, I approve
i've only got into metal this decade, but as for the trends recently I do agree with darkreif, Deathcore and Metalcore have been annoyingly prevalent, and even if they have produced some good bands (Heaven Shall Burn, The Rotted, even Converge - look at how popular they've got this decade) the majority is annoyingly mainstream and generic. Metal has become slightly mainstream the last few years, and scene music has developed a bit more of a Metal edge which appeals to a majority of teenagers that went to rebel against their parents just slightly more than the average little emo child.
I do agree with the black metal comment as well, it seems to have outgrown the former stereotype of what black metal should be like Burzum and expanded onto more avantgarde and progressive extremes. In fact, I think this sort of applies to a lot of genre's, every genre seems be expanding into more avantgarde/progressive boundaries, if the 90's were there to establish the main stereotypes of metal genre's, then the 000's are there to perfect them and I feel like the 010's are there to expand upon everything and wander into more bizarre territories. I'd put a lot of money on the most successful bands for the next few years being the more stranger and expansive than ever before, people just aren't as impressed by your more straightforward acts anymore, because no matter how good something is, a lot of it has been done before, which is both a good and a bad thing. On one hand, we will get more unique, individual music that tries to break borders and not apply to stereotypes. And on the other hand, you'll miss out on more straighforward bands because of this new found need for uniqueness and individuality, but people don't seem to realise, just because something is different, doesn't mean its good - which will result in a lot of bands trying to be unnecessarily strange to appeal to this new overly pretentious market which has been developing for some time and taking it too far.
On the whole, what I've seen of a lot recently is the declaration of genre's running out of steam. Post-rock's not had anything new for years apparently, same with melodic death metal, black metal and thrash (minus the rebirth of the traditional scene that's come back in the last year or so), this means that bands try extra hard to stand out, resulting in more out-there concepts and unique aspects to music that would be otherwise be ordinary. While this creates some really interesting music that works, it also results in some complete shite that just tries too hard. So what I personally see in the next few years is a massive gap in quality between those bands that create some really individual and unique music and those bands that just can't pull it off at all- plus you'll get bands that still play music the old-fashioned ways and get ignored and called generic despite being pretty impressive (this has already begun to happen this year in particular), and while this could create an exciting decade for music, I can see more standard genre's dying out completely, for example, bands who play a style similar to Dark Tranquillity or older In Flames will simply be too old-fashioned to be relevant in the Melodic Death Metal scene, even if they create amazing music. Of course, you'll get comebacks of certain genre's if this does happen, which will be great to see, but overall, I can really see a lot more straightforward and hard hitting music dying out in place of more expansive and outward music in every scene.
Of course, I'm slightly tipsy while writing this, and it's all just my opinion, but I like what I've written
sums up my thoughts nicely.