You won't be screwed at all. Every point you speed in your artifact weapon dramatically increases the cost of the next point you will spend. So if point 1 costs 100 artifact power then point 13 costs 6500 power. What that means is point 14 costs 9000 artifact power. In other word you can forgo puting in that 14th point into artifact A and instead point points 1-13 into artifact B. So if suddenly spec B is better than A, you can switch to 80%+ of A really quickly.
This isn't true anymore. the increase per point is far more linear now. For example, the latest character I just got to 110 on the beta has the first major trait unlocked just by questing and getting the treasures as I go.