I think they usually renews the TPS after 18 months expiration. The situation back home will hardly improve in 18 months. Even if it goes back to normal like pre earthquake, they are way low per US standards and is still deemed vulnerable. So liklelyhood that this could be renewed for 36 or 54 months or even more? Further it is in US intetest to grant such thing to Nepalese being neighbor to China. Just my opinion.