Like many, I'm excited about the MIPS Espressif chips. I have had several on my desk since the end of last year along with with various "programmers" from Tindie for flashing bootloaders, firmware, etc.
At less than $4 for an ESP8266 on ebay, the lack of security support is a critical, if not fatal, flaw.
Until it supports crypto, reliable SSL/TLS connections, and ability to securely store Wifi passwords / credentials in flash - it's a liability to use one of these chipsets for WiFi - not a benefit.