General Android Question

OK, typed all the below, then remembered that 3G is getting turned off, so your phone needs to support at least VoLTE (Voice over LTE) to make calls in the very near future, and the G6 does not. Short story is that you will probably need to upgrade for that reason, but not because of android.

It probably isn't important at all so long as the apps you use still work. You should install security updates as they become available, but I wouldn't get hysterical about it.

Eventually the battery will fail and you may be forced to replace the phone, many folks say batteries will only last 2- years. I have an original Motorola Droid (circa 2010??) and it will still hold a charge.

 

According to this the Moto G6 supports VoLTE on Verizon (assuming you have the US version):
https://community.verizon.com/t5/Br...ied-Unlocked-Android-Smartphones/td-p/1089311
Even the older G4 models and G5 Plus supports VoLTE.

Having 4G LTE isn't the same as supporting VoLTE, and unfortunately GSM Arena doesn't list what phones support it. There are a number of 4G phones that carriers won't enable VoLTE on.

 

Boy, seems the 3G shutdown info has gotten pretty muddy. Here is Verizons knowledge base on phones that will no longer work when 3G is shut down.
https://www.verizon.com/support/knowledge-base-218813/
Money quote for you:

Looks like you should be good until the end of next year, but I see one thing you should already have on your list for Santa next Christmas.

 

I think Verizon charges for WiFi calling. I have Mint Mobile (T-Mo MVNO) and get WiFi calling for free. That is different than VoLTE. Both the carrier and the phone have to support it.

 

When did you activate it on Verizon? If it was after April 30th 2019 it has to support VoLTE.

To see if VoLTE is turned on check here:
Settings > More > Cellular networks > VoLTE
Settings > Network & Internet > Call
(Or a similar location, varies by device where it's located)

Sometimes it's called Enhanced LTE, or HD Voice.

If you can't find it try this, works on some phones:
Dial *#*#4636#*#* on the dialer app.
Tap on Phone Information
Enable VoLTE Provisioning
Then try to find it in Settings again

Assuming your Moto G6 supports VoLTE you might have to turn data on to make calls after 3G is shut down.

Calling other US numbers is free
https://www.verizon.com/support/wifi-calling-faqs/#wifi-cost

 

I edited your post to fix the quote formatting.

Guessing the Voice LTE is it. Honestly don't know why this feature seems to have 4 different names.

This is the page to check if a phone is compatible with Verizon, but since yours is already activated I don't know if it will say "Compatible" or "already in use" instead:
https://www.verizon.com/bring-your-own-device/

Back to your original question, if your phone does have VoLTE I agree with what @Unforgiven has crossed off in his first post above. If you only use apps from the Play Store and don't visit dodgy websites the phone should be fine for a few more years. Of course if you can get a good deal on a new one that's always an option.