Wait for Better Water Resistance
The 2019 iPhones feature the same IP68 water and dust resistance as the 2018 models.
If you're unfamiliar, the 2018 flagships are both water resistant up two meters for 30 minutes. It's an improvement over the iPhone X, but Apple could go higher in 2020.
Nothing if confirmed, but Apple patents have hinted at the potential for improved water resistance in upcoming iPhones.
According to AppleWorld, the company has filed for a patent that could make the iPhone even more water resistant or waterproof by using “vacuum sealed connector” for the device's Lightning port, USB-C port, and other ports.
Now before you get too excited it's worth noting that Apple's is often granted lots of patents and many of the innovations never make it to market.
That said, there's obviously a big demand for a well-protected iPhone so don't be surprised if Apple makes improvements to the design in 2020.