In a year and a half, I can apply for my permanent residence and work permits and those will go in my new passport, thus allowing me to only carry one passport again. However, a year after that, I'll be applying for UK citizenship and, when granted, I'll have to carry both US and UK passports for when I visit the US. The US requires US citizens to use US passports in the US, regardless of their other citizenships, but I'll have to carry my UK passport for when I return home.
This raises an interesting question, though. As a US citizen, it's illegal for me to travel to Cuba without State Department approval (Iran and North Korea are no problem. Go figure). As a UK citizen, it's quite legal. If I only have a US passport, Cuba stamps a separate page to slide into my passport which I can remove when I go back to the US, but otherwise, it's still illegal. So presumably I'd want to avoid those legal shenanigans and hand the Cuban officials my UK passport, but what happens if I visit the US later? If they see my British passport, they would presumably want to thumb through it. Could I be charged with a crime for something that it would be legal for me to do as a UK citizen, but not a US one? Presumably I should beg the Cuban officials to just give me the paper visa to slip into my passport rather than stamping the UK one.
However, this minor annoyance also means interesting possibilities. For example, if I visit Israel, other middle east countries might bar me for having an Israeli visa in my passport, but I can just switch passports!
Two and a half years down and two and a half years to go.