I would like to have a nice Remington 700 in 5.45, but I still do not think it is a viable option for commercial marketing.
The caliber is still largly unknown outside the group of shooters that we make up. Ammo is not easy to find everywhere, i.e., in every gun shop. .223 offers a wider range of ammo, and is more versitile.
Many bolt guns do not like steel cases, although this can be remedied. (More cost)
No commercial manufacturing of the round. This is enough to kill it here. If it isn't being made here, there is a reason. ($)
Lastly, many common calibers are based on similar bolt face dimentions. Rifles with different bolt face dementions are not commnly made. Best example is the 6.5 X 55 Swedish Mauser. In the top 10 of popular calibers, but only a Remington for 1 year, and only commonly made rifle is a POS, overpriced Ruger.
Tooling up for something new of limited appeal is a tough call to make. Maybe someday, but not soon. Especially if the ammo imports are legislated out of exsistance.