Does our oath to the Constitution ever expire?

Cpl Dave D I can relate to your dilemma. I have many blog postings written at "Oh-dark-thirty". The frequency is increasing as we drop deeper into the abyss of progressive interpretations of our Constitution and their shenanigans. So, let's answer your question and get you back to bed so that you can catch up on your beauty sleep.

Your Oath of Enlistment or Commissioning is not enforceable in and of itself. (Can you imagine what would happen if politicians could be held accountable to their oaths which have similiar declarations?) It is merely a declaration that you voluntarily submit yourself to the provisions of the UCMJ so long as you serve. Technically, you remain obligated to that service until discharged.

Morally and ethically, many veterans consider themselves bound by their promise to support and defend the Constitution against all enemies, foreign and domestic, for life. However, that is a personal choice, an honorable choice, the choice of a citizen who recognizes that America is not defined by a land mass, but rather by principles codified in the Constitution. We may pledge allegiance to symbols of the Republic, but in actuality, without the Constitution and dedicated observance of it, there is no nation. It seems that service members and veterans understand this better than most. Sadly, the sum total of those who serve or have served is a scant minority of the nation and the proportion of those who have not learned these same lessons are growing exponentially with every passing generation.

Our oaths never expire.

Cpl Dave D
Technically it expires once our enlistments/commissions are up. BUT, as Capt Seid Waddell says, our Oath never expires. It is our duty to defend the Constitution against all enemies, foreign and DOMESTIC.

Both of enlistment never expires. We may no longer be serving in uniform but is veterans I personally believe we are continually serving our nation in one form or another.

To me a oath never expires. But it is very sad that our elected officials choose to ignore the very constitution that we swore our oath too.

Great question. My answer is no it does not But as we take an oath to defend, i also believe civilians have a duty to know the rights we defend and actively educate their kids.
Ideally, I believe the constitution and citizenship should be part of public school curricula to include small arms training and qualifying to help remove the mystique and fascination and preserve our 2nd amendment and other rights.
I respect the individuals freedom to own or not own a firearm, but their kids are born with that as a birthright. Not teaching them is a very dangerous oversight IMO.

I guess "technically" it does expire after you have full filled your service obligations, but I've never stopped honoring it.

An oath taken between you and your God(or gods), can only end with breaking it. There is no expiration of an oath.

Amendment to remove the constitution? Amendment itself is the constitution, I can't see how that work out. To destroy the constitution, one must violate the constitution.

Seems most are weighing in with their heart, which is a good thing. Any oath is no longer legally binding when the contract under which it is given is no longer in force. Most keep it because it becomes a part of what/who they are. I bring this aspect up because there's an occasional instance of a Vet demanding another Vet maintain their view and value on it. I think oaths are more important than most view but then again I made another oath 39 years ago and still have no intention of breaking it or her heart, ever.

Cpl Dave D
Note that the Naturalization Oath of Allegiance also includes some similar components; specifically that clause "to protect and defend the Constitution of the United States against all enemies, foreign and domestic."

But the citizenship oath also adds "and laws of the United States."

"I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, of whom or which I have heretofore been a subject or citizen; that I will support and defend the Constitution and laws of the United States of America against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I will bear arms on behalf of the United States when required by the law; that I will perform noncombatant service in the Armed Forces of the United States when required by the law; that I will perform work of national importance under civilian direction when required by the law; and that I take this obligation freely, without any mental reservation or purpose of evasion; so help me God."

https://www.uscis.gov/us-citizenship/naturalization-test/naturalization-oath-allegiance-united-states-america

Sometimes I wonder: would it not also be a good practice for American natural born, specifically native-born, citizens to recite a similar oath?

Regarding your question regarding does the oath still apply should the Constitution be changed through Amendment: Yes, it does.