The outfit has offically said that its AMD AM4 300-series and 400-series motherboards will be compatible with both upcoming third Generation AMD Ryzen CPUs and existing AMD Bristol Ridge APUs.
The company said that its engineering team have been working relentlessly prior to the availability of the upcoming CPUs to ensure its products "keep their promise of ensuring customers get the best value without worrying about future upgrades".

Here is a planned list of third Generation AMD Ryzen compatible models from Biostar.

B350ET2, B350GT3, B350GT5, B350GTN, B450GT3, X370GT3, X370GT5, X370GT7, X370GTN, X470GT8, X470GTN, A320MD PRO, A320MH PRO, TA320-BTC, TB350-BTC, A320MY-Q7, A320MH, B45M2, B450MHC, B450MH and Hi-Fi B350S1

It is not the only outfit to offer backwards compatability. The move appears to follow ASUS and ASRock.