I should emphasize block size/weight increase should only be used as last resort, not as first resort or not considered at all.
I believe that if a proposal requires a hard fork, and the network isn't in a life-or-death situation, then it will never gain enough support. It's not as easy as saying that "a hard fork will eventually be needed".
That's my contention too. Some people believe that as technological improvements mitigate the technical reasons not to increase block size, that it will become easier politically to accomplish a hard fork. However, I think the fee market will just become the central political issue at that point. The question of whether fees alone can sustain adequate mining incentives (at 4MB block weight limit) could keep everyone debating for another decade.