There's no doubt in my mind that the next version of the AX-8 will be a variant of the Axe FX III so I'd bet the Amp Boost function will be in it.it will likely be a feature in the updated hardware version that i am convinced is days away from announcement.(disclaimer... i got no inside info whatever)
Even if you were just able to adjust the 10dB of clean boost would already be a great start. This can't possibly take any extra CPU?
If all that's needed is a clean boost to drive the input stage of the amp block then why not just use the pre-EQ and the input gain to achieve what a drive pedal with gain set to 0 and level set to 10 would do ? If the input gain is not sufficient just place a null filter block or a volume block in front of the amp block and crank the filter/volume blocks level dial.