So I confirmed that my Southbridge supports SATA port multipliers, but I don't want to drop the money on expensive external HDD enclosures. So what I want is to be able to support several independent eSATA external drives on my mobo's single eSATA port.
There doesn't seem to be any cheap (or even available) eSATA "hubs" or other external multipliers.
So how about this: An eSATA to USB 3.0 adapter ($18) then hooked into a USB 3.0 hub ($20+). From that hub, I can re-adapt into eSATA devices (at a cost of $18 adapter per device) as well as connect to future USB 3.0 directly. Theoretically.
You can connect an esata drive to a usb 3.0 port via adapter but not possible for usb 3.0 drive connect to esata port because no such adapter exist. And from what I saw, the external esata port multiplier is not that expensive (around 100).
Usb 3.0 port to esata device adapter, yes.
esata port to usb 3.0 device adapter, no.
You are already spending about 60 on your setup for 1 esata device. If you want to plugin 3 esata device, you will need more usb 3.0 port to esata device adaptor, cost you 100 in total, not to mention your setup is not possible. So spending 100 on a multiplier is the way to go.