Only Jim is disliking the fixture because it isn't a standard troffer with full reflectors. But a standard troffer won't fit here. No, we like existing fixtures by and large.
The consensus will be to rip out the ballast and wire ballast-bypass LED "fluorescent tubes".
I'm the minority report. I'm doubling down on the new fluorescent tech. I'd throw a $20 General Electric ballast and four $2 Sylvania 90 CRI real tubes in that fixture, and have better light than you can get from common LEDs. It's all Tier 1 suppliers, the stuff will work for decades. And it's cheap!