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

I don't think all the questions are really worthy to discuss but still I found some of your point much better for the discussion here , most likely one .
1) answer is Exactly no , because if any coin has the same technology like bitcoin have then it don't mean that the coin will give big impact in the market of the cryptocurrency and unlimited numbers of people will enter in that coin to make investment , As we can see there are many numbers of the coins which are having the same technology like bitcoin have but still jave progess not better .
2)I think the condition is already at this condition because if we will pay low fee then confirmation is low and if will pay high then confirmation will be faster , then i don't think any point needed to discuss at higher level about this .
3) This factor no oke Exactly can any one tell because all depend upon future only that what people will accept .
6) I don't think that single currency or particular numbers of the currency can solve the problem because they have not much better technology then what the king have ( bitcoin ) , so here Cryptocurrency other than bitcoin are for trading purpose only at the exchange.