Welcome to KH!
It’s a clever idea for a bag. If you continue the bag will be a slightle different shape and larger or you could stop at the width you would like but have a shorter bag.
You could also switch to 2 increases per row for the main body of the bag then go back to 4 increases on the other end.
It’s really your choice. And of course, you can always rip out most of the body and pick up sts to begin the decreases at 2 per row.