I will be very surprised if they get new IL-76 (the IL-76MD90A version with new engines). Maybe refurbished.
The tri-engine Falcon 8X (size leader among Falcon jets) will also be a surprise. Probably a means to carry high officials in low profile long distance missions overseas without having them use public transport like Biman or Emirates. But this is maintenance-wise a white elephant. Really expensive for what you get.
I'd actually choose the Embraer converted business-interior-equipped smaller jets instead of the Falcon 8X. Falcon 8X will cost somewhere north of $55 Million. For that price you can easily get a business-interior configured smaller Embraer E2 jet (E175-E2) or Airbus A220 jet. Or even a refurbished Airbus A318 business jet for that amount (which is used by droves of Emirs and Sultans from Gulf states). These corporate business jets are much more reliable (larger commercial high MTBO engines which is in much more common airline use) and preferred because of easier/cheaper parts availability).
Another plus point is that you can fit in three times the number of delegates in these commercial business jets (yes, even in luxury seating configuration). If Hasina got one of these - she won't need to use Biman 787's anymore. Most large heads of states in Europe and Asia use these, they don't use commercial airliners.
For my money - I'd bet on the Embraer E175 E2, from a country (Brazil) which is a great potential business partner to our country in South America.
E175-E2
Airbus A220 (actually made in Canada by Bombardier, which was bought by Airbus).