The same iPad 3 users who whined and moaned and groaned that both iOS 8 and 9 slowed down the performance of their iPad 3 models would come back, once again, in angry droves, with even more complaints of slowdowns under iOS 10 or iOS 11.
FYI,
Just because your iPad 3 is no longer able to upgrade to the latest iOS doesn't mean your iPad 3 is suddenly useless.
Your iPad 3 will work as it always has and the apps you have installed on it will continue to update and receive some level of app updates relevent to your current iOS.
You have had four years of iOS upgrades and updates.
Your iPad 3 will still do everything it does now and you will, get, at least, another full year, perhaps two, if you decide you want to wait longer to get a new or newer iPad model.
You’ll just not be able to install any brand new apps that require iOS 10 or 11.
Your iPad 3 is NOT, suddenly, becoming obsolete or useless.
So, your options are really keep using your iPad 3 or purchase a new iPad if you feel you need or want to.
Your current iPad 3 will still work and continue to receive app updates until sometime in the near future when, with the recent introduction of iOS 11, ALL support for older 32 bit iDevices and any iOS 32 bit apps will come to a final end.
Your iPad 3 will still work and function as it always has, but will no longer receive any more app updates sometime in the foreseeable future.
The final app updates your iPad 3 will end up receiving will be their last!
Your iPad 3 should STILL be receiving app updates, currently, but look for this to end at some very soon later date.
I am still using iPad 2 and 3 models and they are still receiving plenty of app updates under iOS 9.3.5.
This is why Apple introduced the new, lower cost 2017 iPad 5 model, in April
Apple is trying to get older iPad 2, 3, 4 and 1st gen Mini iPad users to upgrade to more modern iPad hardware in anticipation of the recent introduction/release of iOS 11, which WILL render all older 32 bit iDevices obsolete, in time.
Good Luck to You!