This isn't that unreasonable especially for a devkit.
For the CPU everyone expects a 8-core Ryzen
For the GPU, we don't know what CU count, but the clock seems ok given that it will be 7nm.
The RAM BW is what a APU with an 8-core CPU and a GPU with 10TF would need. It implies a 384-bit bus with 14-Gbps GDDR6 chips not unreasonable given X1X has a similar setup but with GDDR5.
The 48GB won't be in the retail console, but 24GB seems reasonable. I expect SSD's across the board in nextgen consoles. SSD's will have the biggest impact on the user experience and devs need to be able to design with an SSD as the baseline in mind.
These specs only imply a ~2X boost in teraflops, 2X boost in RAM, a substantial boost in CPU and drive speed. Not that far fetched.