I hope not. The usb flap is the most annoying thing to have on a phone.
Bringing phone into toilet bowl, swimming pool or talking on phone while in the rain or bathing is not my style.
The Japanese models of phones like Sharp, Fujitsu and even the LG22 (LG G2 Jap model) could do waterproof without flap covers for USB and headphone jack. I think Motorola had something like this as well for one of their phones in the US. The user guide did mention the following, as well as short explanation of IPX5 and IPX7:
This product has a waterproof property equivalent to IPX5 and IPX7 on the condition that battery cover is securely attached (based on in-house testing). Specifically, you can make calls holding the product with wet hands in the rain (less than 20mm per hour) without umbrella, as well as use the product in a place with water such as a bathroom or kitchen.
IPX5 equivalent means that the product will maintain its operability as a phone even if it is sprayed with water from a 6.3 mm diameter nozzle at a distance of about 3 meters for more than 3 minutes at a rate of about 12.5 liters per minute from any direction.
IPX7 equivalent means that the product will maintain its operability as a phone with no water getting inside the main unit even if it is gently submerged in a tank of still tap water at room temperature to a depth of 1 meter for about 30 minutes.