Umm, not quite. Yes, there are more stay-at-home options nowadays, however, the market during Titanic and the obstacles for very leggy runs are much the same as they are now.
As someone who tracked boxoffices during those days, Titanic's run was absolutely astounding. Why? Because Home video saturated the market and DVDs were beginning to make inroads. If you're talking Raiders of the Lost Ark or ET, sure we can understand but in December 1997, VHS was not just starting back then. It was everywhere. Replace "I'll wait for it to hit Netflix/DVD/Blu-Ray" with "I'll wait for it to hit VHS" and you get the same impact on attendance. The only difference are illegal downloads.
TLDR: Titanic was not THAT long ago.