A (current or soon-to-be) NIST-recommended alternative to ECC?
To my knowledge, NIST has not really decided or announced anything about successors to ECC. However, they do run workshops and such on post-quantum cryptography, so when the time is right something will probably move towards standardization.

NSA, on the other hand, recently announced that they will soon push for a post-quantum system, going so far as to say that moving from RSA to ECC may be unnecessary in the mean time.

The reason here is not performance or efficiency, however. By many measures the possible candidates for the successor are less efficient. Instead, they want something that remains secure even if quantum computers become practical (known as post-quantum security). Neither ECC nor RSA has that property.

But no, no specific alternative has yet been chosen. Because of this and the above mentioned recommendation to skip ECC, some have even wondered whether post-quantum security is the actual reason for the announcement.