iOS 10/11/12 and iPad 2, 3 & 1st generation iPad Mini Compatibility
The iPad 2, 3 and 1st generation iPad Mini are all ineligible and excluded from upgrading to iOS 10, 11, 12 or any other future iOS versions.
They all share similar hardware architectures and a less powerful 1.0 Ghz CPU that Apple has deemed insufficiently powerful enough to even run the basic, barebones features of newer iOS versions.
Also, both iPad 2 and 1st gen iPad Mini have a paltry 512 MBs ( NOT GBs ) of internal RAM.
No where near enough RAM to sufficiently run either newer versions of iOS.
Most iPads have, at least 1 GB of RAM and all newer iPads have 2 GBs or more of internal RAM, now, which is plenty of RAM to run newer versions of iOS.
In addition, iOS 11 is now for newer 64-bit hardware iDevices, now.
All older iPads ( iPad 1, 2, 3, 4 and 1st generation iPad Mini ) are 32-bit hardware devices incompatible with iOS 11and 12 and all newer, future versions of iOS.
Why would you want to even consider upgrading an older iPad, anyways?
Since iOS 8, older iPad models such as the iPad 2, 3 and 4 have only been getting the most basic of iOS features.
Older iPad users get none of the newest and coolest cutting edge features that newer model iDevices, with better hardware specs, can handle with more aplomb.
Plus, the iPad 2 and 3 are the only two supported models left that use the much outdated 30 pin dock connector.
The same iPad 2 and 3 users who whined and moaned and groaned that both iOS 8 and 9 slowed down the performance of their iPad 2 models would come back, once again, in angry droves, with even more complaints of slowdowns under iOS 10, 11 or 12.
FYI,
Just because your iPad 2 or 3 is no longer able to upgrade to the latest iOS doesn't mean your iPad 2 or 3 is suddenly useless.
Your iPad 2 or 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 and five years of iOS upgrades and updates.
Your iPad 2 or 3 will still do everything it does now and you will, get, at least, another full year, if you decide you want to wait longer to get a new or newer iPad model.
Your iPad 2 or 3 is NOT, suddenly, becoming obsolete or useless.
So, your options are really keep using your iPad 2 or 3 OR purchase a new iPad if you feel you need or want to.
Your current iPad 2 or 3 will still work and continue to receive app updates for some time, when, with the recent introduction of both iOS 11 and 12, ALL support for older 32 bit iDevices and any iOS 32 bit apps will come to a final end.
Your iPad 2 or 3 will still work and function as it always has, but will no longer receive any more app updates some time in the foreseeable future.
The final app updates your iPad 2 or 3 will end up receiving will be their last!Your iPad 2 or 3 should STILL be receiving app updates, currently, but look for this to end sometime soon.
This is why Apple introduced the new, lower cost 2017 iPad 5 model, in AprilApple 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/releases of iOS 11, and now iOS 12, which WILL render all older 32 bit iDevices obsolete, in time.
So, the decisions are really up to you!
If you decide to stick with your older iPad until it is no longer getting any app updates, I would STOP using that 2-2-1/2 year old Safari web browser, as it is, probably, not safe and secure to use any longer, and seek out a third party web browser that is STILL currently being updated and STILL being supported on iOS 9.3.5.
Here are a few third party web browsers that I know are STILL being updated and supported on iOS 9.
Popular third party, iOS 9 and earlier compatible Web browsers are more quickly dwindling, now.
iOS 9 users are now down to 6 current and up to date, popular third party Web browsers, now!
iCab Mobile Web browser
Dolphin Web browser
Dolphin Incognito Web browser
Snow Bunny Web browser
Private Browsing Web browser
Maxthon Web browser
Good Luck to You!