So, the issues I've run into with current tech 1mm LED direct view displays is that it is a VERY inconsistent technology that has a VERY long way to go and is VERY expensive.
That's a lot of 'verys' right there.
I've used the Planar direct view displays and while performance has been decent, it hasn't been out of this world. I got to watch the Superbowl a couple years ago on a 17' diagonal 4K setup that I programmed. Planar had come in and done their calibration of the panels to ensure image uniformity... But, that's what it took. They had to come in and they spent a few days calibrated a double 4K display - so about 33' wide. It was a lot of work on their part.
If we had to exchange a single panel, then it would need to be calibrated to the rest of the wall.
Price: About $750,000.
The seams were still visible and readily apparent between the different displays despite a great deal of time butting them up against one another accurately. It's apparently not as easy, or as clean, as manufacturers would like you to believe that it is.
'Just add some tiles!' is the claim, but the reality remains that it is far more difficult than that to achieve.
Front projection being replace with a inexpensive direct view LED solution, including OLED, is certainly a nice goal, but a usable 150" diagonal 4K setup can be put together for under $3,000. You can find a few 85" displays around that price point, but forget anything larger. The 98" TVs are $10,000+ from what I've seen.
Nothing over 100" has anything approaching real world pricing.