Don't Wait If You Can't Wait Until April 2020
Don't wait for the OnePlus 8 if you can't wait until April of 2020, or more realistically, if you can't wait until May.
Almost every year they announce their first phone in April and release it around May, then another during the second half of the year. The OnePlus 7 debuted in May of 2019, and we're expecting a similar release timeframe for the OnePlus 8.
There is a small chance OnePlus moves things up to better compete with the Galaxy S20, which is coming out on March 6th.
That means you'll need to buy a OnePlus 7T Pro right now, or wait a while for the 8. All while Samsung, Google Apple, and potentially multiple other brands release great phones.
Basically, if your current phone is struggling and you don't think you can wait another 2-3 months, buy something else right now or in the near future.