If he continued northwest across the Arabian Sea from Kalhat, Marco Polo would most likely describe Hormuz.
The city of Hormuz is located in current-day Iran, and it is located northwest from Kalhat - also known as Qalhat - which is located north of Sur, in Oman. This is the route that Polo took in his returning trip from China.
On the other hand, both Dhofar and Socotra are southwest from Kalhat, also in Oman. Also, while Venetia is northeast from Kalhat, it would be the last city he would have described after visiting Kalhat.