Yeah, I think it's possible. But it takes a while to build up, just like any true form of love.
As far as the whole competitive thing - maybe what helps build that kind of friendship / brotherly love is shared competition. In other words, the two of you competing together, against a common challenge.
That challenge need not be another person. When I went to college, I majored in a very tough department. I had a good friend that I met in my first week of freshman year who wound up majoring in the same subject as me. We spent a lot of time studying together and helping each other out, class after class, semester after semester - in addition to hanging out and doing all the usual buddy things. By senior year, I realized that I loved him - not in a sexual way at all (I didn't even think of myself as gay back then) - but in the way you described, because we had grown up together and had these shared experiences.
This happens in warfare all the time - and yeah, I know that's a sensitive topic for you, but it's also the one where I've most often heard of this kind of bond between straight guys happening. Soldiers in the same unit who have been through combat together, looked out for one another, maybe even saved each others' lives, will develop the kind of love for each other that you're talking about.
I remember reading a story about a bunch of guys who came back from France after WW2 with a bottle of cognac. They all made a deal that the last one alive would get to open & drink the bottle. If I recall correctly, after the 3rd-to-last one died, the other two agreed to open it and share it with each other. This was 50 years later...
It may also be an age thing, come to think of it. Those soldiers and my college buddy and I were all in that 18-22 age bracket... maybe that's just the age at which guys are most able to form those kinds of relationships with each other. I remember going to my college's Reunions last summer and seeing my cousin's class, who were celebrating their 40th Reunion, partying like they were undergrads again, and thinking, wow, that's some serious bonding.