SoaDA was not my cup of tea ether, but i sure didn't want to see it fail.
IMO DOTA type games don't do very well. Look at Demigod. It kind of fell into the abyss too. This niche i think only DOTA dominates. The question is "Why?". Why does DOTA succeed, and all others based on DOTA fail?
The problem isn't that DotA games don't do well. League of Legends, Smite, Awesomenauts and probably Heroes of the Storm all do fairly well for themselves. So why have Dawngate/SoaDA/Infinite Crisis basically everything else failed? The problem is you need an absolutely massive marketing appeal to reach the critical mass of players required to get decent matchmaking going. Post-release SoaDA had basically no people playing it. Why? Well, we can look at successes and see what they've got going for them.
LoL: It was the first free to play entry. It also helped that it had a big marketing budget. You could also make the argument it was the first standalone product. Yes, Demigod was there before it, but Demigod had massive netcode problems on launch. GG Overture was also before it, but trying to sell a PS franchise on the Xbox, especially in Japan is a recipe for failure not to mention the gameplay is quite different from what we expect from MOBAs today. (which is kinda sad since in many ways Overture was ahead of its time)
DotA: Specifically, DotA2. DotA2 unsurprisingly converted much of its initial audience over from the DotA1 which is pretty much the same game except less shiny. Being the flagship title to sell Steam to people also does not hurt.
Smite and Awesomenauts: These two games differ extremely in their style of gameplay from your standard MOBA. Smite plays much more like an action RPG and Awesomenauts like a platformer. Thus, there's a much higher chance it will appeal to a different type of player than those already invested in another MOBA. Which is important because there's typically a large amount of time that needs to be invested into a MOBA to play it. So instead of trying to simply poach disenfranchised players they can get "new" players in. Smite also had the unique monetization where it's either microtransactions OR pay one price for everything.
HotS: Is attempting a radically different approach. "Casualising" the game (in my opinion) does little to nothing to actually distinguish your game from competitors. However, that plus marketing your game to the userbase of ones that don't typically play MOBAs (Diablo, WoW, Hearthstone players) might give you a solid chance. It is yet to be seen if this will hold. Another game that's trying this that no one here's probably heard of is Lord of Vermilion Arena, which is largely trying to convert its large arcade following. Though that might be a regional thing. I don't think many game companies have servers in Japan. (that aren't Japanese themselves)
SoaDA was only really first in terms of its quest system, which wasn't enough (similar to how a slightly different map and some side objectives in the form of the spirit wells was not enough for Dawngate). It also couldn't convert its previous playerbase. And it wasn't a unique monetization (fairly sure there's nothing left, but hey maybe someone's really original). Why is it important to have something unique that you can market or some audience you can convert? Because there was one game with that that LOST that element and pretty much failed after. Heroes of Newerth. HoN was basically a standalone DotA (except not really cuz it didn't emulate some important things), but once DotA2 was "released" that basically sunk that game.