Countdown to the Global Flood in Genesis?

Yesterday morning I was talking with my prospector friend Stormie Waters and her fiancé Roland Meadows, and the topic strayed from their upcoming nuptials to the Genesis Flood. God brought the animals to Noah, some other things, then we pondered Genesis 6:3.

I picked up my Bible and read, "And the LORD said, 'My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years'". It looked like a countdown to me. Roland said that the key word can also be translated "abide."

The Entry of the Animals into Noah's Ark, WikiComm / Jan Brueghel the Elder, 1613
When considering the meaning of a word or phrase, it is helpful to see how it is translated in other places. Aside from Genesis being an ancient text, the Hebrew word in question is used only once in the Old Testament! Is it strive with man, or abide in man? This is not a vital point of Christian doctrine so there's no need to stand and defend a hill on this. However, it is useful to examine what is going on.
There are two main interpretations of this statement. The first is that God is setting a limit on human lifespans, and the second is that God is starting a clock that counts down the time to judgment. These can be labeled as the lifespan and countdown views, respectively. Deciding which of these is the better interpretation requires a deeper study of the text, but as we will see, both of these positions require the interpreter to make some assumptions, so we should remain somewhat tentative in our conclusions.

You can read the article in its entirety at "Longevity or Countdown: What Does the 120 Years in Genesis 6:3 Refer To?"