Too late for that now. It could have happened 26 years when Somaliland was first created, but the path dependency has set in, and a shift of economic activity away from Hargaysa is unlikely. A decsion in 91 to make Berbera the capital would have by now given Somaliland a third economic center and would have relieved the population pressure faced by Hargaysa. It is going to be very difficult to convince businessess and people to move from Hargaysa to Berbera now that the former is basically the center of politics and business.
The funny thing is that Somaliland recreated the same situation that existed in the Somalia they wanted to escape. They complained of overcentralization, and when they got the opportunity they overcentralized.
26 years ago Berbera was virtually destroyed during the civil war in the 80s. It was even more damaged than Hargeisa since it was the regime's final stronghold before retreating back to the south.
There was no choice but to centralize since there wasn't enough resources to build a new capital city from scratch. Hargeisa already had government buildings left behind by the regime so they were just taken over and used by the Somaliland govt.
Plus Berbera would not be a suitable capital anyway because of it's high temperature in the summer and with Hargeisa not being that far away. Which made Berbera only a transit for goods going to Hargeisa markets.
But if you go there now you'll see a lot of buildings going up and people buying land in anticipation of the port upgrades.
You can also see a similar boom in Wajaale on the Ethiopian border. Both Wajaale and Berbera will be major commercial centres in the next 10 years. Especially with Hargeisa becoming overcrowded.