They didn't start actual work on the ride until earlier this year, so I'd say it's still under 2yrs. (remember, it was a late addition to the FLE plans).
Beyond that, i'd still give them some extra leeway with the ride construction. Since it'd be in a landlocked location surrounded by disney guests once they open BoE and LM, I can easily see that causing some delays with construction since it would limit their ability to move supplies and debris into and out of the construction area, as well as some bigger work that might require cranes or other heavy equipment.
Honestly, I'd be willing to place money on the bet that the site access and guest safety concerns are why we are not only seeing vertical construction so fast (all the steel work... and maybe even track laying), but that it's one of the primary reasons why BoE and LM aren't opening earlier. (not a ton earlier mind you, but as soon as they open those areas to the public, they lose a lot of freedom with the work on he mine train. a delay of a month on the attraction openings could translate to 3months of delays in construction due to being limited to overnight hours if the attractions were open that month.)
