Now, "indie rock," like "alternative rock," can rarely be construed 100 percent literally:
Many so-called indie labels are subsidiaries of corporate monoliths, and those who aren't frequently have deals with gigantic distribution networks, big-budget streaming services, and other godzillion-dollar mega-entities. At once, as you suggest, lots of the prevailing values and aesthetics of indie-rock music have intersected with (and been absorbed by) the mainstream with techniques big and small. When Arcade Fire and Bon Iver are going gold and winning Grammy Awards — the former for Album of the Year — it's hard to see them as scrappy underdogs, no matter what labels release their records, and regardless of how their members might view their relationship to the music industry.
As a writer and editor, my frustration with the descriptor "indie" isn't so much about purity, or even accuracy; it's about its failure to explain a lot of anything. Technology has managed to get easier than ever to replicate studio slickness on a tiny budget, to the point where low fidelity often sounds like an imaginative decision rather than matter of necessity. Which, consequently, ensures that independence — real or imagined — needn't translate into anything that can be heard in a recording. Indie rock certainly qualifies as a type, and we generally know indie-rock music when we hear it, but it's hard to pin down one prevailing sound predicated on method of distribution and marketing.
For provided that I've been paying attention to such things, I've heard — and rolled my eyes at — proclamations a given cultural entity is "dead." Is indie rock dead? Is punk dead? Is rock itself dead? Is criticism dead? A lot of the time, "dead" is code for "irrelevant," and relevance tends to reside squarely in a person's eye of the beholder. If you're tired of something, or if it benefits you in some manner to proclaim something irrelevant, then you're infinitely likelier to proclaim its death than you'd be if you're to arrive fresh. You and I aren't ready to proclaim indie rock dead, but we canacknowledge that it's splintered to a point where in actuality the term has lost a lot of its meaning or value.
Finally, I'd encourage anyone and everyone to rebel against blanket dismissals of "bland Top 40 drivel." In the same way indie rock now includes music that's found mainstream success, music with major distribution, and music that doesn't rock, the Top 40 includes music that's often inventively recorded, beautifully produced, emotionally stirring, and hard to resist. We're bound to stumble across genius where we expect to get drivel, and vice versa.