PSoC5LP has got ADCs with max 1Msmpl/s so, when multiplexed this could work.
You did not tell the needed precision for the ADC, PSoC5 has got 2 SARs and an ADCDelSig, so from this side you will not meet a limitation.
USB-communication can impose a limit since the transfer is not guaranteed to be contineous all the time from the view of the connected PC. So some buffering algorithm seems to be needed.
Is the datastream contineous or is it limited to a time.
What are you using the data for on the PC-side?
Development kit for PSoC5 LP to be found here www.cypress.com/.
The SAR OR SAR sequencing component will deliver 12 bit performance at 1 MSPS,.
I2S can handle up to 96 Khz, SPI to 18 Mbps.
The DelSig can do 16 bits at 48K SPS.