It’s great that you are concerned for the impact on other users 
If there is a TTN Community near by (Note I haven’t looked!) if you are not a member please join, then use the Console messaging facility to let the users know or alert the initiator as it may be easier for them to send a general message. Remember also if there are other communities close by your gw may also be providing some additional coverage at long range and likely on high SF’s… so may be good to let the initiators of those know too. Also given you are likely running through Meshed.au probably good to let @Maj know also (as this message has just done!) in case he hears of user problems after the fact or know of nodes that may be affected and can help give the users a heads up. Also he & local team may be able to guide you better on the transition and any Meshed associated aspects.
Please give notice where you can & don’t rush to migrate gw due to user impact, unless you know there are others that can take the slack for V2 deployments…think months vs days or even weeks.
@Maj recently posted of their experience with the V2-V3 transition