I don't buy the DSLR failure, simply because it's not about the DSLR's. It's about the system. That is why A Mount didn't do "really well". I can't say I know if it was a complete disaster, I don't think it was. Clearly the it was neglected, never got the investment in deserved, had far too many missing/old Minolta lenses (some good, some less so), many lenses remained screw drive never updated either. Around 2013/2104 A mount was on the back burner, buried by Sony - minimal interest. So no question market share slid or was on the dive around 10 years ago.
Prior to that no, they never were near Canikon, but they were way ahead of Pentax (who are still making cameras). You can't get near the big players if your system is lacking.
Look at what Sony did with E Mount, how much they put into it - everything. Vast number of lenses, including many which were obvious A mount never turned up ones (cough 70-200mm F4, cough 85mm F1.8 etc etc big list). Tons of marketing, huge "influencer" hype. DPReview also part of the Sony hype machine (sadly), trying to convince us just how much difference mirrorless makes. Yes Sony have done well with E Mount, are we surprised with what they threw at it? If Sony put half that effort into A Mount, it would have been able to rival Canikon or get closer. People can enjoy their "Next best thing", many of us will have fun picking up the cut price bargains they dump onto the used market down the road
