ML is naturally a part of TA, when done as analysis of "technical" price-volume data. Any more, and you start to include the fundamental realm of markets. This is simplified understanding and everything can be mixed together also, probably even favourably so. I think the consensus here is reasonable, although people tend to argue about differences in semantics rather than finding common grounds.
Anyhow: I believe everyone agrees that given raw market data input, nobody here expects to plug in a generic ML/datamining algorithm or two, and then wait for a consistent trading plan and execution from the computer. You have to have some basic trading idea, data mine the possibilities (manually or semi-automatic) and then make a first attempt at a prototype. This is true for all technical trading, and you don't even need an ML algo. ML like everything else is just a tool. It's ass-backwards design to include it, if you don't really have a use for it yet. Instead, you include ML in your trading engine when you clearly see it can fit a specific need. Doing it the other way may provide much learning experience, but may waste alot of time towards a working implementation as well.
What ML may provide is more dynamic non-linear analysis and rules based on deeper statistics. In that way, the same algo could provide many different trading setups, mined from the data itself. So you have more automation in the analysis part of your trading engine. Or it could just be used for one specific little need or anything a little more involved than if-then-else.
This may sound great, but everyone who's had anything to do with software development, know from experience how hard it is to make something work in all circumstances. Such a general method as ML is even harder to create, monitor and maintain. Additionally, possibilities for analysis is endless, and ML doesn't really solve that problem of narrowing down the problem/questions in the grand scheme of things.
If the trading engine learns from new data continuously, you'd need to quality check that process continuously as well, as all kinds of artifacts and biases may develop over time. A static ruleset is easier to maintain, but will of course lack the adaptivity you may get from ML.
This is all very general, and may not be applicable to every implementation, but nobody is discussing specific implementations here yet.
There's no reason you can't make money in the markets, with or without ML, other than lack of faith - which is the basis for most successes in life. Ie. There's always up-front cost and risk that needs to be paid. Of course, one must create a trading plan as one has to mitigate being wrong most of the time, which is natural in most trading except scalping. So to anyone planning to "trade with ML", learn trading first, as ML won't make anything "easier" (although it may perhaps simplify the trade engine parts it's replacing!).