Steam did really come along way from 2007 when I joined it first, I really can't imagine my gaming done in any way other than via Steam, sure I do play games off Steam but I consider my main platform and gaming life on Steam.
Steam ofc isn't flawless and in recent year of them trying to be more open and friendly to indie developers with Greenlight and workshop, things didn't really turn out well and we have seen an influx of shit undeveloped games and a bombardemnt with "new titles" that just became a joke from developers of cheap casual games, Steam needs to take that control back, be more serious with their quality control or else you will be floded with crap and the only thing that will stand out are either big big AAA titles vs the rest of the crap and some real gems will be lost in the mass of crap. I will not even touch the early acess thing, that is a subject for itself.
Also I hope they don't lose the track of what I wrote above with their push into living rooms and competing with console market. Maybe the above is planned in such way just because of it, I wouldn't know.
All in all big up for Steam, let's just hope they still remember the PC crowd in the years to come, the crowd that made them what they are today