A whole host of questions that I feel are important. Any insights would be appreciated!
1. Can blockchain-based currencies really work with billions of users?
2. Will it become a choice between impractically expensive fees or impractically slow transaction confirmations?
3. Are the proposed plans for BTC and ETH scalability just short-term fixes that will eventually run into the same problems later on?
4. Are DAGs the solution?
5. How much time will IOTA transactions take if each user has to process their own share of the "tangle"? Can tiny IOT devices even handle such processing requirements?
6. Others have suggested that currencies such as DCR, PIVX or BURST solve the problem in different ways. If so, how?
7. Are there any other solutions?
Thanks

In answer to question 7. Supporters of Xtrabytes believe it is infinitely scalable. Firstly the blockchain is built on a rock solid secure foundation unlike any other chain. On top is a virtual layer that cant be hacked and as its virtual the understanding is there is no friction and has no scalability issues.