No, "heaven and earth" do not exist today. Not the "heaven and earth" that Jesus was speaking about. We bring so much of our own worldview into Scripture that we have a hard time understanding Bible terminology.
The heavens and earth refer to the Jewish dispensation.
"The vision of Isaiah the son of Amoz, which he saw concerning Judah and Jerusalem in the days of Uzziah, Jotham, Ahaz, and Hezekiah, kings of Judah. 2 Hear, O heavens, and give ear, O earth! For the LORD has spoken: "I have nourished and brought up children, And they have rebelled against Me;" Isaiah 1:1-2
Now, is God speaking to all of the Earth here? Is He speaking to the heavens? No. He is speaking to Israel; according to context, to "Judah and Jerusalem in the days of Uzziah, Jotham, Ahaz, and Hezekiah".
"But I am the LORD your God, Who divided the sea whose waves roared; The LORD of hosts is His name. 16 And I have put My words in your mouth; I have covered you with the shadow of My hand, That I may plant the heavens, Lay the foundations of the earth, And say to Zion, 'You are My people.'" Isaiah 51:15-16
When did God create the Heavens and Earth? According to this passage it was when He divided the Red Sea. No, I am not denying the physical creation as described in Genesis 1, but that is not the topic here. And - once again, focusing on this passage in Isaiah - what were the accompanying results of this dividing of the Sea?
1. The planting of the heavens,
2. The laying of the foundations of the earth, and
3. The saying to Zion, "You are My people".
It is this "heavens and earth" Jesus is referring to in Matt. 5:18.
Peter, writing three decades later, but still before the Parousia, describes this same heavens and earth:
"But the heavens and the earth which are now preserved by the same word, are reserved for fire until the day of judgment and perdition of ungodly men." 2 Peter. 3:7
Peter is looking forward to the time that Isaiah had written of:
"For, behold, I create new heavens and a new earth: and the former shall not be remembered, nor come into mind." Isaiah 65:17 (KJV)
Once again, we have a hard time appreciating the context of Christ's words because we are so attuned to our own understanding of the phrase "heavens and earth", not the Scriptural intent.
2 Peter 3:7 are the same Greek words and the verse reads "But by His word the present heavens and earth are being reserved for fire, kept for the day of judgment and destruction of ungodly men." Again no meaning of nation Israel but of the Heavens and in cotrast to Heaven the Earth. Peter was quoting the Isaiah 65:17 verse therefore from His use of the Greek it would again means the literal Heaven (sidderal and sky) and the earth as a whole.
Going back to the original language shows the meaning as a literal heaven and earth. When God seperted the Red Sea He established in Zion a nation of people He called His own.