I think MOBAs are probably the single most interesting Genre as it's one that has only been developed and flourished 'recently'. Sure the original DoTA is old as hell and everything is still being perfected now, but from my knowledge it's the only true 'new' genre to pop up and get super popular. Everything else like Roguelikes, Puzzle-Platformers, FPS-Arcade-RTS-RPGs are all just hybrid mixtures.
Now of course, with an ENTIRE new genre, there is a lot to explore. Like with fighting games or action games or more recently, MMORPGs, they have different IP to use. With MOBAs we see this happening in full throttle as the MMO market dies down.. Infinite Crisis is the Marvel IP, Heroes of the Storm is the (true) Blizzard IP, I wouldn't be surprised to see a Star Wars MOBA sometime down the line either, maybe even something as crazy as LoTR.
The problem is, in my opinion, is that it's easy to compare this to what happened with MMORPGs.
The two graphs below show the GLOBAL subscriptions for MMOs between 1m - 12m subs and 150k-1m subs.
There are three things that really stand out to me in these that I think will replicate in MOBAs.
Firstly. World of Warcraft is by far and large the BIGGEST game out of the lot. Sure you can make arguments about certain games having multiple subscriptions for multi-boxing, botting etc but as every game has a similar amount of this and it's incredibly hard to keep track of, let's just use these numbers. So WoW is the biggest. By a pretty big margin. It always has been, and sure it's dwindling in numbers BUT, so is every other MMORPG out there.
Secondly. games specifically made for their respective IP (Warhammer Online, Age of Conan) have SPIKES in popularity when they release due to the original fanbase, but then they die, quickly. This is usually because the WoW players in this case see a similar game mechanically with a recognizable IP and quickly want to experience that, but soon they realise it really is just a weaker version of the original in multiple ways (mechanics, UI, even just the graphic design that they're used too) and go back again.
Thirdly, SANDBOX titles increased the most steadily over time. Second Life and Eve have both steadily increased over time with relatively little losses over the entire span of the games. They retain their userbase and just add more, which is why I believe Everquest - Next was trying to branch out into that field with the house/fortress building etc.
So with MOBAs, I see a lot of games coming out specific to certain IPs, but I believe they'll only get spikes in popularity and then fall off heavily. With the pure amount of cash being pumped into LoL and DoTA through leagues, tournaments, sponsors, and the fact that both of those games have had more time to be balanced (HAHAH JK) and developed mechanically to the point where no-one has the patience to wait through ALPHA and BETA stages of the new games.
It's also harking back to the old question. If I've spent 100+ days of my life playing WoW, why would I throw it all away?
Same goes for MOBAs, accounts usually have some sort of level, you invest money (even if it's f2p BAR DoTA) to boost your champion pool etc. Plus the fact that each MOBA has so much information, what would drive you to ditch all your previous knowledge that you've invested to much time into.
Obviously, people do, people always will, but does it make a big difference in the overall outcome? Not really.
DoTA and LoL have enough differences that they will both stand to make a lot of money, with LoL maybe edging ahead because of the insane things RIOT have done in terms of the LCS and I think it has a little bit more global appeal due to that.
Other MOBAs will live and become cash cows for their respective IPs but will never be anywhere near those two. Idgaf which gaming organisation have teams for SMITE. They're just doing it because the game has such a small playerbase, if you get the top 5 people in that small playerbase then they have a big chance of winning everything, which means easy money for you. Doesn't mean the game is popular or has a big market share.
tl;dr - DOTA&LOL > MOBAS BASED OFF OF ANY OTHER IP. I ONLY MENTIONED SMITE ONCE BECAUSE IDGAF.