McCullum yesterday announced he was giving up keeping in test cricket to extend his longevity.
He will continue wicketkeeping in twenty/20 and one-day internationals.
"I have talked to a lot of people about how they went about extending their international careers, including some prominent former and current wicketkeepers," McCullum explained in a press release.
"I am passionate about playing for the Black Caps and by limiting my keeping to the shorter forms of the game it increases my chances of prolonging my career."
Germon, who played 12 tests, would like to see McCullum concentrate on scoring runs at the top of the order.
"I think he provides the opportunity for us to win test matches through the way he could open the batting," Germon said.
"He'll score at a decent clip and all the successful test nations around the world have opening batsmen who score at a decent rate and help set up the game.
"I think if you have someone at the top who can score quickly, then you have a really good chance of setting up your team to win test matches.
But batting at No 5 you save test matches rather than win them."
While Germon believes McCullum is well equipped to succeed at the top, he warned the transition from all-rounder to specialist batsman was a tricky road.
"It will be interesting to see how Brendon goes in terms of playing as a batsman only in test matches.
It is a very difficult transition both mentally and physically to suddenly adjust.
As a keeper-batsman, scoring runs is pretty much a bonus.
But when you play as a specialist batsman the expectations are that you will contribute consistently and significantly every time.
"Not many have done it that successfully.
But I think Brendon has the skills and mental capacity to give it a really good go."
Wherever McCullum bats in the order, and he is perhaps no longer considered a certain selection, he will leave a big gap at No 7 and behind the stumps.
Germon believes Auckland keeper Reece Young shapes as the best replacement.
"I'd be surprised if he wasn't the next one in line. He is an experienced player now, and whenever I've seen him keep he hasn't let himself down. He will be a very capable international gloveman. How he compares to Brendon, I'm not exactly sure."
Former Otago wicketkeeper and Young's provincial team-mate, Gareth Hopkins, has been the back-up keeper for McCullum in limited-overs cricket and will also come into contention.
"Personally, I feel that Reece just shades Hoppy in terms of his glove work. But I know that they [the selectors] view Hoppy as a very good limited-overs batsman."
Northern Districts gloveman Peter McGlashan has been "pigeon-holed as a twenty/20 specialist" and appears earmarked as a limited-overs player rather than a test keeper, and Germon puts Otago's Derek de Boorder and New Zealand under-19's Tom Latham (son of former test player and one-day opener Rod Latham) in the up-and-coming ranks.
Meanwhile, Ross Taylor will captain the Black Caps side to contest the Tri-Nations series against Sri Lanka and India in Sri Lanka in July.
The selectors named a 15-strong squad.
Regular captain Daniel Vettori is skipping the tour to attend the birth of his second child, and McCullum is also taking a break following a busy season.
Wellington duo Grant Elliott and Jesse Ryder return from injury, and Kane Williamson is rewarded for excellent domestic form.
