A 17 year old no longer gets you the 2k tax credit?

Right.  Has to be UNDER 17.  Now you get $500 for other dependent.  A couple years ago they increased the age to 18 but that was only for 1 year.  Now it went back to 17.

Correct.   The dependents age at the end of the tax year is his or her age for purposes of determining how much credit one qualifies for.   That dependent will qualify you for the $500 other dependent tax credit.   

To qualify for the Child Tax Credit, your child must meet all of these requirements:

• Be under age 17 at the end of the tax year
• Is your child, stepchild, foster child, adopted child, sibling, step sibling, half sibling, or a descendant of any of them (for example, a grandchild, niece, or nephew)
• Has their own Social Security number
  • Children with ITINs don't qualify, but may instead be eligible for the $500 Credit for Other Dependents
• Lived with you for more than half the year
• Didn't support themselves (didn't pay more than half their own expenses)
• Is a U.S. citizen, U.S. national, or U.S. resident alien
  • Residents of Canada or Mexico don't qualify