SSDs maybe much better than HDDs when it comes to access speeds, read/write speeds and I/Os per second but HDDs still have one area where they blow SSDs out of the water. That is in the cost per gigabyte. These technologies that you list are all related to increasing the areal density – i.e. the amount of data that can be stored in a given area. Without these advancements, SSDs would catch up to HDDs in cost per gigabyte a lot faster which would spell the end of HDDs a lot quicker.
There is a problem that I see with this though, technologies like HAMR, shingled recording, and helium filled drives seem to be stuck in the upper end of the market with the lower end stagnating. A 2TB HDD has only dropped by about 40% in cost in the past 5 years while SSDs have dropped about 75%. In my opinion, this is because 2TB HDDs are the sweet spot in terms of data storage required by the average user – if you browse OEMs computers from the likes of Dell and HP, you will notice that a vast majority come with a smaller SSD for the system drive and a 1TB–2TB harddrive for data.
It is my opinion that once 2TB SSDs approach the cost of 2TB HDDs (~5 years or less), you will see HDDs disappear from the consumer market and only remain in the enterprise realm where high capacities are desired/required and margins are much higher.
To the person who suggested that areal density should be changed to a real density, areal density is defined as “a measurement of the amount of data that can be stored on a given unit of physical space on storage media. It is most frequently measured in gigabits per square inch and used to describe hard disk drive capacity.”