Yep, you're doomed. Jk. If you really want to customize your computer get a Desktop PC.
Yeah, there is no chance of that happening. Laptops have their CPUs basically welded to the MoBo. To try and remove it is as folly as it sounds. Another major problem is that almost nobody sells Laptop CPUs because of this.
There is no i3 337U it either a i3 3227U, i5 3317U, or i5 3337U
U models can't be changed out as they are BGA (soldered to the board) M and QM models can be upgraded. You will have to look to other means of improving performance or suffer through.
This is the laptop trade-off. Portability vs price, performance, and upgrade options.