Fernando long-term Mendis replacement in Test?

Following the consolation win against England in the third Test, Sri Lanka seems to find a different solution for the number three spot which was occupied by Kusal Mendis for a long period of time. 

Mendis though rated highly by many ex-cricketers and members of the media, has not been able to justify his place in the side. He was dropped once during the 2-1 Test series defeat to England but, returned to the third Test. However, he still wasn't able to make a solid contribution to the team and it was reported that Oshada Fernando who has been in rich from for Sri Lanka A in South Africa had been called up for the squad. 

Fernando has already played 21 Test matches for Sri Lanka, mainly as an opener averaging little under 35, but whenever he has failed, he certainly didn't have the same backing that Kusal Mendis had been enjoyed for nearly a decade now. 

Fernando scored 122 and 80 against South Africa A last week which saw him getting a call-up to the national setup. 

Pathum Nissanka who was also not considered for Test cricket for a long time, made a gallant comeback at the Oval, leading Sri Lanka to a famous win with a stunning century in the fourth innings. 

Nissanka looks set to open the batting with Dimuthu Karunaratne who has been short of runs in the recent past. So, selectors must be considering the possibility of Fernando replacing Mendis at three. 

However, the other question that the selectors must answer is, what next for Nishan Madushka? 

Madushka also has had some success batting up the order but he didn't have a very good series in England, but Sri Lanka had to make him keep wickets due to injuries and changes to the team which didn't help his cause, given that he has to bat at the top as well. 
 
It would be unfair to him, should he be axed from the side based on his performance in England, especially because he is the youngest (25) of that Sri Lankan Test batting unit.

Moving forward, selectors may look to rotate Fernando and Madushka at three, while rest of the batting line up in Test cricket looks solid.