Aviation industry seems to slowly pick up, in general. I can't comment of latest aviation infra developments in KUL, PEN, KCH and others, but here in BKI there is an obvious on-going construction on the taxiways for the past several months now (Google Earth image attached for reference). Does anyone know what is the construction for? On a more general outlook, I don't think there would not be any airport expansion or relocation for the next decade or so. Passenger traffic has been decimated for more than a year now. If aviation traffic continued similar growth trajectory in 2020 from 2019, passenger numbers could have breached 10 million for the first time.
It could take perhaps at least five or even up to 10 years to reach the 2019 level, give or take. And COVID-19 has altered the way we conduct businesses and meetings. There is no need to travel to KUL or beyond just to attend some 1–2-hour meetings. That can now be done simply using Zoom, Google Meet or Microsoft Teams. Leisure trips could pick-up, as many people say - 'revenge tourism', out of lockdown, and in need of mental release. But would the experience be the same as before? In Venice, it is suggested that tourist numbers should have a limit, because the city was, in pre Covid era, overly touristed. During lockdown, nature seems to thrive, but with tourists slowly coming back, some people fear that the calm that came with covid will be gone. What about in Malaysia, especially tourism dependent Sabah?
Therefore, I could imagine a secondary airport like BKI will maintain its size for decades to come, with minor expansion. For one thing, the airport is conveniently close to KK. I live only 10 minutes away from the terminal. Most of us in KK do live some 30 minutes away from the airport, traffic conditions permitted. If one issue emanating from BKI towards overall development challenge in KK (height restriction), is the runway position, not the terminal. I think the present runway should be decommissioned, and a new one should be built further out at sea, away from heading directly towards KK CBD. Or shortened present runway to just half of its length (leaving southern portion only) to accommodate lighter planes like ATRs or small business jets (like LCY) operations. And full-length runway (4,000M) could be built further out at sea.
The remaining decommissioned parts of the airport could be redeveloped into something else, like large public park (something KK really lacks, despite being marketed as nature resort city).
Anyway, this is my point of view specifically on BKI though.