OR is currently forecast to still have 5 CDs after 2020. That fits very well with the current projection of Multnomah county to have almost exactly 20% of the state population. A 5 CD split can preserve the UCCs (3 CDs for the Portland UCC) and keep whole counties with less than 2.5% deviation from the quota.
However, OR is on the bubble to gain a 6th CD, so it's useful to look at that as well. Multnomah will be too large for one CD and going south with the new CD requires chops to counties and UCCs. If the counties along the Columbia are combined with Clackamas and the remainder of Multnomah, it is possible to create a 6 CD plan that only splits Multnomah, chops no UCCs, and stays with 2.5% of the quota.
That 6 CD plan would be very, very competitive. It'd make DeFazio's area much less safe, probably end Greg Walden's political career with Presidential turnout (unless he moves from Hood River) and that new Salem/Corvallis district would probably start as a Lean D tossup.