The LORD is the portion of my inheritance and my cup; You support my lot. (Psalm 16:5)
The Lord is our portion. The word portion here is not to be understood as part of a whole. It is defined as our destiny, what we are destined for, our heritage, or more precisely predestined for. We are marked for Him. He is also our cup, He becomes our sufficiency in both food and drink. Everything we need for life, He fulfills for us. The reference of the "lot" may either speak of the land or it could mean the whole quantity, everything we will ever have on Earth and all we will have in Eternity with Jesus. All that is involved in our earthly life and our eternal life in Heaven. It is wonderful and comforting to know how God is in control of Everything, every single thing past, present and future, including our destiny and the promise of a Heavenly lot which Jesus says in (John 14:2)
“In My Father’s house are many dwelling places; if it were not so, I would have told you; for I go to prepare a place for you."
The picture of Heaven that Jesus paints here with many dwelling places. I believe it will look more like how ancient Jewish and Roman communities lived at that time, then the common perception of Heaven as each person living in their own separate mansion.
The majority of people in ancient Roman times did not live in separate dwellings or homes as we do now, or even separate apartments in a large complex. They lived in sprawing interconnected building called Insulas. They housed most of the urban population that included ordinary people of lower or middle-class status as well as the wealthiest from the upper-middle class. Only the elite or the very wealthy lived in a "domus," which was a large single-family residence, however, both kinds of housing were intermingled in the city and not segregated into separate areas or neighborhoods. It was all one large neighborhood. They would always have a central courtyard where everyone would meet to trade, sell goods, have community gatherings, meals. The local synagogue would be near the courtyard area as well.
From this verse I see Heaven as a perfect Insula, a mansion with many rooms. It will be a place filled with Peace, Joy, and Praise (Rev 7:15-17), and your room is being prepared just for you and it will be the portion of your inheritance, your cup and your lot, together with all the other saints.
"If it were not so." Jesus is very clear and direct in His words, that He would have told us if the situation would have been any different, but He didn't. By saying, "if it were not so," He is preventing the situation from being any different. It is, what and how He says it is. It will be so.
We Will have a room in His Insula; He is preparing your room in Eternity right now while you are reading this. Now that is powerful and awe inspiring, and certainly gives me goosebumps and great comfort everytime I read those verses.