We cant really tell what your gpu going to be like in 2-3 years down the line. Games will evolve and be more powerful and they could require more GB in gpu. If you think its best to upgrade your new GPU then there some new ones coming out this month with 16GB and that will work good in your comp for many years until you wanna upgrade again!
Yes its doing really good for 1080p 144hz gaming so far. I just have to change my power supply from 400 wats to atleast 600+ and get a new case with like 5-6 fans. I recently fried my ssd because of heat. 700 gb of games gone I thought it was my gpu but its my power supply. Rx-5600 xt needs 500 wats and I only have 400.