Dubuisson lost on the 23rd hole of an epic final with Australia's Jason Day at Dove Mountain, but only after threatening to pull off a truly astounding victory.
Three down with six holes to play, Dubuisson won the 13th and 17th with birdies and then saved par on the 18th from a greenside bunker to force extra holes after Day three-putted from 65 feet.
However, the real drama was yet to come as Dubuisson looked to have wasted all his hard work when his approach to the first extra hole bounded through the green and came to rest in a seemingly unplayable lie underneath a cactus.
Undeterred, the 23-year-old somehow conjured a pitch onto the green to within four feet of the hole, from where he holed for par after Day had saved his from a greenside bunker.
Day showed little emotion at Dubuisson's remarkable escape, but even the 26-year-old was left smiling wryly and shaking his head in disbelief as his opponent repeated the trick on the next hole.
After pulling his approach to the par-four ninth into more desert bushes, Dubuisson casually pitched out and calmly holed from seven feet for par after Day had missed his birdie attempt, prompting US Ryder Cup captain Tom Watson to write on Twitter: "Two of the greatest up-and-downs I have ever seen Victor!!!"
The next two holes were halved before Day finally sealed victory with a birdie on the fifth extra hole.
Dubuisson had the consolation of £545,000 for second place which, coupled with his earnings for winning his maiden European Tour title in the Turkish Airlines Open last season, means he is set for a Ryder Cup debut at Gleneagles in September.
McGinley told Sky Sports: "It looks like with the points he has accumulated he is a nail-on now. If he was 90 per cent before the week he is 99.9 per cent now. With all the evidence we have seen this week I think he will be a very welcome addition to the team.
"You can't help but be very impressed. A lot of us were all learning about Victor and the fortitude he has shown under pressure all week has been most impressive."
Dubuisson, who had recovered from three down after four to beat his idol Ernie Els on the 18th in the semi-finals, added: "I am disappointed because I made some terrible shots, I missed some shots at the end.
"Jason played very well and he made the very important putts. Any time I had a gimme birdie he made his putt. I was very impressed by his nerve."
Day, who beat Rickie Fowler 3&2 in his semi-final and climbs to a career-high fourth in the world rankings, said: "Obviously I didn't want it to go this long but Vic has a lot of guts and a great short game. The guy (saves par) straight out of the cactus twice and for a 23-year-old kid he has a lot of game and you are going to see a lot of him for years to come.
"I think the biggest thing was how much do I want to win. I kept saying that to myself last night and visualising myself with the trophy and I am just glad I could finish it off."
In the third/fourth place play-off, Els birdied the 18th to keep the contest alive, only for Fowler to make his own birdie on the first extra hole.