Needless to say, more pixels don't equate a better picture per se, as they are usually made tinier to fit the count, and collect less light, all other things being equal. With the magic of pixel-binning, or combining information from several pixels into one, however, not only is the resulting photo file smaller in size, but also the snap itself is usually able to overcome the smallish pixel size.
We can imagine the amount of pixel-binning that will be happening with a 64MP sensor, resulting in a nice 16MP photo if four pixels get folded into one virtual like how the current 48MP sensors churn out perfectly usable 12MP shots.
If you hoped that Samsung will be having this sensor in a phone when the Galaxy Note 10 lands, however, you will be sorely disappointed. As mentioned, more pixels don't automatically equate a better picture, plus Samsung is likely to go with the S10+ setup for the Note 10, just situated vertically instead of horizontally.
What phone will Samsung use its new 64MP camera sensor in first, then? Well, a Xiaomi one, according to one Chinese leakster. Ice Universe has posted that "the international premiere of Samsung's 64MP sensor is in a mysterious model of the A series, while the domestic first is a mysterious model of Redmi." That's right, the Galaxy A70 was rumored to carry this thing first, but the announcement came and went with a 32MP shooter.
There's still an eventual Galaxy A90 to be announced in the new series, but in the meantime Xiaomi may very well beat Samsung to the punch and grab the 64MP juggernaut with Tetracell technology that bins four pixels into one virtual, is able to record 480fps slow-mo, and would sport a second generation phase detection autofocus. We'll be all ears.