Welcome to understanding what Revelation 22 I believe is really saying. Looking at just Revelation alone can be confusing. However God is not the author of confusion and he gives us more than one witness. Isaiah also gives us more detail to unfold this mystery.
It's commonly believed in the New Heavens and New Earth there will be no more sin, no more marriage, no more kids, whoever gets to heaven that will be it there will be no more people getting into heaven there is a finite limit. However that is not what the Word of God teaches. The Bible teaches that Jesus Church will continually increase Isa 9.7 and it will be an eternal church for many generations Isa 60.15. Contrary to what is taught by modern day teachers that there will be no more oceans that there will be just one big land mass where everyone lives we see in Isa 60.9 that will be ships in the New Heavens and New Earth yet most teachers want to say we will just have spiritual bodies in the New Heavens and New Earth.
The gospel message of Jesus Christ is going to go all the earth, starting with Tarshish first, an area near the tip of Spain. In Isaiah it says these areas have not heard of the fame of Jesus Christ referring to the time of the New Heavens and New Earth, yet today we certainly know the majority of Spain or these areas have now heard of Jesus Christ therefore we know this New Heavens and New Earth was in the past and continues today.
We often think that in New Heavens and New Earth that there won't be money, however Isa 60.11 tells us that the nations will bring their wealth to the church and that gates of the city are not shut day or night Rev 21.25. You can come to The Holy One Of Israel (Christ) at any time you don't have to have to have a high priest to enter the holy of holies for you. You can enter into God's presence anytime through Jesus.
It's also commonly believed or taught that before Christ can return the temple must be rebuilt for him to dwell on earth, however the Bible says Christ is the builder of the temple not man, Zec 6.12.
Again it's commonly taught that there will literally be no more sin in the New Heavens and New Earth. That idea or teaching is actually for the righteous of God, those whole believe on Jesus The Christ and do his commandments Rev 22.14. We see in Isa 60.12 that nations that won't serve Jesus will perish.
..... Stop back to find out more about what the river coming out of the throne is in Revelation 22.1-2 is. For those that just can't wait here is a preview of what Isaiah says; Isa 66.12. If it isn't obvious the Gentiles flow now or are part of that river. Christ is the living water that flows out the throne of God and we the believers in Christ are that stream. More to come.....