1) Bandwidth is pretty irrelevant now. Even players on cellular networks have megabits of bandwidth. I stopped spending a large amount of time optimizing for packet size while building the networking for Dota 2. Nobody is playing a 14.4k modem anymore.
2) Server placement is still an issue. It's still ~200ms round trip from New York to Sydney for example. Fortunately, cloud infrastructures can make getting servers to closer your players much easier now. You don't have to physically install servers into data centers in the region.
3) Packet loss still occurs, but is incredibly rare that the gap between using TCP and UDP is narrowing. Modern TCP implementations like Microsoft's are amazing at handling loss and retransmission. However, I'd probably use QUIC for game networking if I was to write an engine from scratch these days.
2) Server placement is still an issue. It's still ~200ms round trip from New York to Sydney for example. Fortunately, cloud infrastructures can make getting servers to closer your players much easier now. You don't have to physically install servers into data centers in the region.
3) Packet loss still occurs, but is incredibly rare that the gap between using TCP and UDP is narrowing. Modern TCP implementations like Microsoft's are amazing at handling loss and retransmission. However, I'd probably use QUIC for game networking if I was to write an engine from scratch these days.