Actually, Portuguese brand AJP ALLREADY done it :-)
Its called the AJP GALP 125 Enduro.
(There is also a 150 version).
20 hp (25 in the 150), 9.5l fuel tank bellow the seat, 98kg dry weight (that includes KS+ES, very narrow
thanks to air cooling, alu. swingarm w/o weldings Paioli fully adjustable suspensions
with the rear with a reservoir and the front is a USD 46mm, Excel rims, Grimeca Hubs, Magura-style handlebar, etc....and a incredible (SMALL) price tag :-)
As usual, Yamaha will take the credit even if
Euros done it long before Yam ;-)