The 1 MB block limit threatens Bitcoin's ability to function as the global reserve currency. It should eventually be changed to 10 GB per block to handle tens of billions of transactions per week.
Future scenario:
Paychecks are sent to billions of people in the form of bitcoins twice a month. People fund online accounts with bitcoin transfers once a week to do a majority of their transactions off the blockchain. No one runs a full node anymore, it's just too expensive. Instead everyone uses a SPV client and countries keep copies of the full blockchain to keep each other honest. Each country's government mines bitcoins and uses the transaction fees to fund government projects.
Fees per KB are around 20 satoshi or 2 USD, so peer to peer transfers are affordable, but rarely initiated because the opportunity cost of spending old bitcoins is just too damn high. The floating transaction fee formula everyone has agreed on effectively limits the average number of transactions to 6 per person per month. Because of this, everyone divides their bitcoin balance into thousands of addresses to accrue confirmations in case their bitcoins need to be quickly spent. Around 50M transactions are included in each block, giving a block reward of 100M USD from fees alone. Governments are smaller and more cost-effective with their spending so the 100M is just enough.
The price of a bitcoin is 10M USD and fiat is nonexistent.