I can only speak for myself, but the jump from $10 to $15, then to $20 (and beyond) for the "premium" indie titles is what pushed me away from them. That and the prices going up in Canada.
I'm far less likely to take a plunge on a game that now costs almost
triple what it used to only ~10 years ago, doesn't have a demo, and can't guarantee backwards compatability. It's why I buy all of them on PC now. Not only do I get the best-looking version, but it's cheaper and will work essentially forever.
Another factor I feel he missed out mentioning is the standardization of retail titles being available digitally as well, and often at sale price at or below indie pricing. For some, they think, "Why would I buy this indie game for $25,when I can get this couple-months old 'full' retail release for $30?"
Whether that's a "fair" comparison or not, I feel it's at least part of the issue they're facing.
That there are too many bad games flooding the store each Tuesday and that games get ignored easily not only months later but a few weeks later including hm games which are of a higher quality than most indie releases.
Maybe being on steam where some genres take off will also help them. Possibly having cheaper sales and it's a positive overall.
I agree that the PC crowd can be more amenable to certain genres. If, however, you think that having too much crap in the store is responsible for their poor sales, then a Steam release would, in theory, be a disaster.