i am between sizes on harley shirts, and so i buy the size up...i have several longsleeve all cotton shirts and through 3-4 hot water washing and hot drying cycles i have been able to shrink them about a half size.
the point being, this too is all cotton except for a little lining in the sleeves. you CAN shrink it if you wash it in hot water, and dry it hot. but if you follow the instructions, and go cold and air dry or gentle dry, it will likely not shrink on you.
as a note, i have purchased this and plan to wear it as a shirt in cool weather...first thing i will do when i get it is wash it several cycles in hot water and hot dry. this will make it softer and fit a bit better for me, but i doubt most purchasers will want to do this.