That was good in 2002. Not now. Lot of people left SWTOR because of lack of endgame content. Players (new ones) won't wait, if after couple of months, there isn't enough, they will leave.
Customers are way more volatile today unlike one decade ago.
True that we have no idea on how much content will be actually in at release timing (or at 30 days after release (end of free month)). End of the free month, 2nd month (end of first paid month) and end of 4th month (end of 90 days billing period) will be deadlines for SE to deliver.
If within 60~120 days after release there isn't enough content (real content and not farm hamlet defense all day long to get a relic), people will leave, it's as simple as that.