In theory, Bitcoin is will scale even to visa level txs and beyond based solely on technological advances. The probability of that happening is actually 100% unless we somehow fail as a civilization, have a 3rd world war, a meteor hits earth etc etc. Otherwise, in 20-30-40 years, a 10gb block will be the equivalent of a 1mb one. It's like PCs went from kilobytes of ram, to megabytes, to gigabytes and home connections went from a few bytes per second to megabytes per second.
Bitcoin will never scale to Visa levels or beyond if you're talking about on chain transactions. Never.
If you make an assumption of ever-increasing technological means, it will *definitely* happen. The only question is "how long before it does?".
Home connections in the 80s/early 90s, were like a few hundred bps to 1200-2400 bps. That's bits. Now there are fiber 1gbps connections in some places.
CPU processing abilities that are now in a simple smartphone, used to be "supercomputer" stuff that filled up entire rooms:
http://pages.experts-exchange.com/processing-power-compared/Obviously, you can just sit and wait for the day when tech will allow you to do more, or you can optimize your modus operandi to make the most of what you have right now.