The result means the Black Caps slip behind India and just above Australia in the test championship standings, meaning the will be relying on Australia to lose one of their three upcoming tests in South Africa, or for India to lose two of their four upcoming tests against England to reach the final.
Williamson said the Gabba test was "amazing" game of cricket and the series as a whole was "incredible....we know how hard it is going across to Australia and playing against them - they're a formidable side."
He said the test championship has certainly created another layer of interest around the game but knows their hopes of making their Lord's final are out of their hands.
"It's a mathematical thing and things you can't control, so you watch from afar and just wait and see how results go and where that might leave us...but we'd love to be in a final should results fall our way."
Williamson however won't be urging on South Africa against Australia.
"Personally I try not to get too carried away with supporting one or the other and just let play their cricket and just see what happens. The test championship without a doubt has brought a really cool dynamic to the curly end of the comp."
So by the numbers here it is.
New Zealand still have a decent shot at playing in the World Test Championship (WTC).
As well as taking India to the top of the standings, the three-wicket win in Brisbane on Tuesday dropped Australia from first to third and moved New Zealand into second.
Due to the Covid-19 enforced cancellation of several series', the teams to play in June's WTC title decider at Lord's were being determined by the percentage of points each team won from the total number of points they had played for.
The result at the Gabba left India on top on 71.67 percentage points, with the Australians falling to 69.20 and behind New Zealand's final percentage points total of 70.
That mark of 70 was the one to watch for the Black Caps, who just needed Australia or India to finish under that number after they each played their one remaining series in the WTC window.
Australia were set to play three tests against South Africa, with New Zealand getting a place in the final if the Australians were unable to secure at least two wins and a draw.
Black Caps fans would also be celebrating if that series failed to go ahead, with the Covid-19 situation in South Africa still threatening the cancellation of those matches, which would leave Australia stranded behind New Zealand.
India, meanwhile, were hosting England for four test matches.
Anything less than two wins and two draws for India in that series would also have the Black Caps booking their tickets to Lord's.
But Black Caps fans wouldn't be cheering too strongly for the English, whose faint hopes were still alive.
An England win in the second test in Sri Lanka and an unlikely 3-0 win in India, or an even more improbable 4-0 win, would allow them to snatch a last-ditch berth in the final.