First-order effects

• Microsoft has the most at stake in this argument: the Office blog post amounts to a defense of a franchise — Exchange, Outlook, Hotmail — whose core product is the channel being declared moribund.
• Consumer mail providers face a demographic squeeze at the top of the funnel, since teens reported by comScore to be abandoning web email are tomorrow's default users.

Second-order effects

• Vendors are pushed toward feature convergence — bolting social feeds, chat, and status onto the inbox — the exact direction the 2007 Wall Street Journal piece flagged, so the incumbents' response risks validating the challengers' premise.
• Social networks and messaging services gain pricing and attention leverage over the communication market, forcing email players to compete on integration rather than on the protocol itself.

Third-order effects

• If each tool wave since 2007 prompts another obituary while email persists, the likely structural outcome is segmentation rather than replacement — personal chatter migrating to newer channels while formal and commercial correspondence stays put — though which segments hold is genuinely unresolved.
• The recurring obituary cycle itself becomes an industry dynamic: every platform shift reopens the question, and vendors' public rebuttals become part of how the market reads the health of legacy protocols.