I will be in the same boat once I move to PR.
I will have Federal for the remainder of my life, Massachusetts state taxes for dates prior to the move in the last year.
My income will come mostly from Social Security and occasional draws on my IRA which I hope will be rare. Once I reach 70 1/2 I and everyone else is required to draw from their retirement funds a certain percentage which varies based on estimated longevity.
I plan to head to PR around mid 2018, so that means I will file state tax for 2017 and part of 2018, and obviously Federal as usual. But once I file my 2018 taxes (in 2019) there will be no state taxes or PR taxes either. Since I will be mostly getting Social Security, only part of the Social Security is taxable, the worst case is 85% of the Social Security being taxed or less depending on how much in total you make a year. If you have other sources of income once added together, there is a table that states what percentage of the Social Security income is taxable. Also as you get older, (age 65+) you get an additional deduction if I remember correctly so your taxes go down more.