In a way, we are getting back to the "old" T2 operations before covid when traffic was higher than now. You checked in at T2 but took the train to the T1 gates. At the time, there were more airlines with check-in at T2 including some full-service airlines like Thai airways.
Yes, funny, isn't it? And interesting to see HKIA describe T2 as being "served by some 15 airlines which mainly operate short-haul and regional routes", while medium- to long-haul will remain at T1. This implies that while some carriers like Thai and Singapore Airlines could relate to T2, perhaps also Air China and EVA, their long-haul Star Alliance siblings such as LH and LX would remain at T1. Wonder what that means (if anything) for the prospects of a Star Alliance-branded lounge at T1 or T2?