Competition for places in Sir Clive Woodward's squad is still fierce, but Brooke - who played in the All Blacks' victorious series against the Lions in 1993 - believes it will not make much difference whoever makes the final 44.
"I think the Lions will lose the series three-nil," he told the Western Mail.
"Look at the 2001 (Lions) side now and a lot of those players have since fallen by the wayside.
"The New Zealand side, on the other hand, is on the way up going by what they did on last year's end-of-season tour.
"They can only get better and grow in stature from the type of performances they put together against Wales and France.
"That leads me to conclude that there will only be one winner - and they won't be wearing red."