First of all, I don't have TPKs very often. In fact, I can't remember the last time one of my campaigns ended in a TPK (if one ever did, in fact). It's certainly been decades since that happened -- probably the early 1980s, if it ever did happen.
So this is a difficult question. "Ordinary" suggests it is a routine event. It most certainly isn't routine. At all.
The timing of the TPK, however, is everything.
If the TPK happened towards the end of the metaplot and the good guys lost, that's it. We're done. Bad Guys win; Good Guys lose. It's over.
If it was at the very beginning of what was planned to be a long-running metaplot campaign, it might be that we would restart with other characters. I don't think it's likely -- but it is certainly possible.
Otherwise, the question of whether I am even going to continue as GM/DM is very much in doubt. I ordinarily take a break between campaigns and somebody else in the group will rotate into my GM spot in our gaming circle. A TPK towards the later stages of the campaign is likely to provoke a change of campaign, era and possibly even game system. It would be a monumental event that would takes weeks if not months to sort itself out.
There would be nothing "ordinary" about it at all.
TPKs have happened from time to time (twice that I recall) in the campaigns run by one of the other GMs in my gaming circle. Those events have resulted in a complete end of the campaign and a complete switch in game systems, too.
Again, it has been a "game shaking/world changing" event. A TPK is not the end of the party - it's not even the end of the campaign. It's been the end of that entire game system being played in our group for quite some time.
There is one other TPK that I can recall that ended on the final encounter with the Drow Queen in a 3.x campaign. The Good guys lost; the Drow won. There was nothing to continue, that was the end of the cmapaign, win or lose. I was not a player in that one, but the DM was a good friend of mine and seemed to blame itself on how it ended. I thought it was not an unsatisfactory result and would reinforce to the players in subsequent campaigns that they really can lose. In short, the downer TPK ending in the final battle was a set-up for the next campaign being all the sweeter.
The players it turned out, were equally as philosophical. It was a good year before he DM'd a campaign again, however. These things take time and have consequences in our gaming group.
I appreciate that others may have very different experiences. I can't speak to those - all I can relay is the experiences in my own gaming group.
[Edit: System Test to see if edit has been properly reflected. Please ignore.]