No. Gurman actually said that the CURRENT Macbook Air starts at $899, not that the newly expected Macbook Air with usb-C will start at $899. No one knows how much anything new will start out at, but there are rumors that there will be a $200 uptick across the board for all upcoming Macs.
Prices are informed speculation as of right now. The rMB is priced at $1299, the same price as the current entry level 13" rMBP. Based on this information, it wouldn't make sense for the new rMBP to start that cheap. That is unless they cut the rMB to $999 or something, but then the Air would fit better at that $1299. Either way, expect to pay more for the new 13" rMBP.