Yes one day could be a million years. According to Gerald Schroeder the universe is ONLY 6 days old if you look at it from the beginning. Each day is actually half the length of the day before it. The reason is light does not age or decay. That is why we can still observe the universe when it is a trillion of a trillionth of a second in age.
http://www.wired.com/2013/03/new-planck-data/
Yes, there are several ways people can look at that verse. As I said ...
1. Could it mean time has no hold on God?
2. Could it mean each day of creation lasted 1,000 years?
3. Could it mean that for each day of creation God would allow 1,000 years of human history?
4. Could it mean the very unorthodox interpretation you asign to it? "A day is 1,000 years. We are very close to the beginning of the 14th day."
I'm sure there is even a 5th and 6th.
Some people take 3 as the explaination based upon this from the Gospel of Barnabas.
15:4 Consider, my children, what signify the words,
He finished them in six days. They mean this: that in
six thousand years the Lord will make an end of all
things, for a day is with him as a thousand years. And
he himself beareth witness unto me, saying: Behold
this day a day shall be as a thousand years.
Therefore, my children, in six days, that is in six
thousand years, shall all things be brought to an end.
......Now I understand the Gospel of Barnabas isn't in the bible and can't be relied upon, but Barnabas hung out with Paul. Was Barnabas correct? Who knows.
Currently I choose number 1.
Number 3 could be feasible. If Bishop Usher was correct with his date of creation being around 4004 BC...and us now being in 2,015 AD....we either passed the 6,000 year mark or are very close to it. If the earth was made 10,000 years ago then Barnabas was wrong.