Age 67 would have a lot of side-effects...
You'll see more younger pilots reporting older pilots for deviations and mental lapses.
You'll see more pilots at all ages going out on disability due to failing any new tighter medical screening, especially mental agility testing.
You'll see pilots out on medical leave at some airlines simply continuing to receive loss of license disability insurance for an extra 2 "free" years.

There are costs to everything. I predict age 67 will cost a lot, both in terms of money and in terms of people who currently can keep flying under current medical exams but may not pass tighter screening. And don't forget, anyone who fails tighter screening will then get disability payments to 67.