If it continues to be operated by a PMCO 777-200 then it definitely will have lie-flat seats. You can ignore the configuration on seatguru without lie-flat - it doesn't exist anymore.
I just did a quick check and it appears to just be an issue with the website - it doesn't appear that the aircraft is being changed.
Even if a PMUA 772 was used on the route the vast majority of these are reconfigured as well, although it's worth pointing out that the seat config being shown on ua.com doesn't indicate that this is changing.