with a ten million console install base? nope. Probably the PS4 will have a 20 million install base when Uncharted 4 launches, so I guess it can do 4 million in the first year, with some luck. 6 million lifetime.
PS4 is over 10 million sold and it isn't even a year old, it will be way past 25 million by the time UC4 launches.
OT: I do think it's possible. People kept doubting the sales of ND games last gen so it's only fitting that they doubt them again this gen. Though I do think it will depend on how much Sony bundles it. 9-10 million is definitely possible.