The Insider will become as optional as car ownership in most of the United States (i.e. not), but it won't be by the intention of Mearls & company. No, their bosses will push it because the shareholders of WOTC and Hasbro will demand it because they want MMO-level profits to maximize the value of their shares. The Board of Directors for both companies will go along with this, and they in turn will direct the officers to make it so. It's a short stop from there to making the online gaming component--already accessable 24/7, with databases and play space and chat/VOIP features--into a very primitive MMO by putting a persistent--"Living"--world into place.
You can play when you like online now. You can choose your fellow players. You have access to the new hotness in D&D 24/7 now online, and a persistent world is one that the publisher controls- and it will be compelled to make it as player-friendly as it can be, which will greatly influence the entire hobby in the manner of a shockwave. This is a plan of incrementalism, and it is foolish to claim that it won't happen; WOTC is now in direct competition with Blizzard for hegemony, and WOTC is in the underdog position in this fight. It's a matter of adapt or die, and you can bet that the people that call the shots and sign the checks will opt to fight fire with fire instead of with ice and water.