There is a related suggestion thread regarding upgrading transfer impossible
This one serve as more generic suggestion, not particular to any country. As stated in that thread, the only way to upgrade an airport to make transfer possible is by sending information to AS why the airport should be upgraded. So this thread suggest to add feature to enable airline to invest on transfer impossible airport to make it transfer possible, allowing the airport to be utilized as connecting hub.
Since I am only familiar with my country situation, allow me to use it as example. I am fully aware that different places might have different situation. This only serve as an example and by no means to generalize a variable factor.
Please use following link as a reference:
Apparently CGK/WIII in Greater Jakarta area, being a big regional hub and heavily congested, without foreseeable development has frustrate airlines that one of them is big enough to invest in Jakarta's secondary airport HLP/WIHH which is located right at the middle of Jakarta. The big airline also planned to developed another airport BTH/WIDD, a regional airport in Sumatra, just 56km south of SIN/WSSS, into domestic and international hub for the group.
Both airport mentioned here HLP (3000m) and BTH (4000m) are two big airports with good infrastructure in place to support growth and connecting traffic. Both are build by government and not by private airline, but government allow airlines to further invest and develop the airport with certain concession rights. In AS both airports are transfer impossible.
By using these two airports as example, I am not suggesting these two airports to be upgraded (although it crossed my mind to send email to support after this), but rather to show that there are airports like this around the world that can potentially be utilized by airline in AS should they were allowed to develop a transfer impossible airport into transfer possible one.
Hope this suggestion can make a nice discussion topic. ^_^