While Nikon USA calls the D7100 the new flagship this is what Nikon Global says: "Reduced from the D7000, the D7100 weighs a mere approx. 675 g/1 lb 7.8 oz (body only). With excellent capturing power, exquisite detail reproduction and depiction performance encapsulated in this compact, lightweight body, the camera demonstrates great agility. The body is also durable as it employs magnesium alloy for the top and rear covers."
"As a middle-class DX-format D-SLR, it features a highly sophisticated design, which satisfies pride of ownership."
I beleive the D400 is coming and when it does it will be a great camera. One with 7-8 fps or more, and built like the D300s or the D800
Check out what the say about the D300s: "Nikon DX-format professional-level performance with agility and creative versatility."