Device upgrade
should I upgrade to an iPad 8th gen? Currently on an iPad 6th Gen wifi, or should I wait for the 9th Gen to come out?
iPad (6th gen) WiFi
Based upon your needs, only you can judge if the expense of an upgrade to a more recent model of iPad is worthwhile.
As for future models, until announced by Apple, nobody here can offer definitive comment and to specifications or capability - and Terms of Use that govern our participation here disallow speculation.
The 6th and 8th generation iPads are capable of running current iPadOS14.x. You can directly compare specifications of past nd current models of iPad here: