To be fair, this is little different to buying a game on the PlayStation Store or Xbox Store. As soon as those go offline, you will no longer be able to download those games.

And so you'll be at the mercy of the lifespan of the hard drive. You won't be able to copy the games to another device as it won't be able to validate ownership.

To be fair, PlayStation and Xbox have a lot longer and reliable track record compared to Google products.

And so, you'll be at the mercy of the lifespan of yet another Google product.

An Xbox can play all games that have already been downloaded and all physical disks indefinitely, regardless of whether you have internet or whether Microsoft's servers are up.

While correct, that was not the point made in my comment. For downloaded games, once the service has gone offline, you are at the mercy of the lifespan of the hard drive.

If I had a physical disc, I could just buy another when it goes bad.

Not sure about Xbox because I haven't owned it in a while but PS4 lets you copy your system drive to a new drive pretty easily. The function is even built into the OS. I switched out the hard drive to an SSD using this technique.

It only works as long as the console is signed into the same account as used on the original hard drive.

This isn't being fair, this is projecting valid fears of a new service and comparing them to other platforms that haven't experienced said fears on any scale to make such a comparison valid to begin with.

We all know when MS or Sony get punched, they come back and swing harder. When Google gets punched, are they ready to dump another billion in to surviving or will they cancel and run? Google isn't known for long tail losess on new launches.

Nowadays it's very hard to own a game. Unless you buy on services like GOG, which offer DRM free installers. You don't really own your games on Steam or Origin and they can remove your access at any time without a warning.