The Talmud Yerushalmi, Pesachim chapter 10:1, gives many reasons why the Mishnah states we must drink 4 cups the night of the Seder.
- The "4 expressions of Geulah" from Shemot 6:6-6:7
- The 4 times the word cup is used in the dream (Breishit chapter 40)
- The 4 kingdoms (i.e. from Daniel) which rule over Am Yisrael
- The 4 cups of wrath that Hashem will pour out on the nations
- The 4 cups of consolation that Hashem will pour out for Am Yisrael
See the Gemara here for the exact verses.
The GR"A says (though I am unable to find the exact source in my Haggadah this year) that the 4 cups correspond to 4 periods of time.
- This World
- The Days of Moshiach
- The Resurrection of the Dead
- The World to Come
I would propose that this corresponds to what is written here in the Raya Mehemna.
- This World - From the time of Exile through the time 1st Geulah of 5708, up to the 2nd Geulah.
- The Days of Moshiach - From the time of the 2nd Geulah of 5727 until the 3rd Geulah
- The Resurrection of the Dead - The start of which is between the time of the 3rd Geulah and the time of the 4th Geulah. On another level of understanding, Am Yisrael will reach the level of "days of old" in this era, as if Am Yisrael of old is the dead that is resurrected
- The World to Come - As mankind reaches higher and higher after the end of the Geulah, it will be akin to Olam HaBa here on earth, the 7th millenium, etc.
May we all be zocheh to eat from the Zevachim and the Pesachim in the final Beit HaMikdash.