A Gen5 G34 would almost certainly use the same Gen5 G19 locking block that is used in both the Gen5 G19 and G17. That means a Gen5 G34 barrel would fit a Gen5 frame only, which in turn would accommodate no earlier G34 barrel. The RSA would be the same used in the Gen5 G17, and no other RSA would fit.
Glock completely redesigned the locking block used in the Gen5 G17 to be identical to that used in the Gen5 G19 and thus made the Gen5 G17 frame, locking block, barrel, and RSA completely incompatible with all earlier generations. Glock made this major change for only one reason...to allow one less part to be stocked by FBI armorers. There were NO performance improvements behind this change...it's just a FBI admin and logistics issue.
Does all that sound like a major change that would benefit ANY purchaser of a Gen5 G34?