Now you can see 1 billion is not a very large number when it comes to internet applications, but your not going to be building facebook anytime soon, so lets take a more practical example.
You are a cloud service provider and operate a Software as a Service business, that means you operate services that people and businesses can lease from your company.
Now your company grows and you have 100's of businesses using your service, within 2 years you have 200 businesses using your service, eventually you have a few thousand. Now you have to support these businesses and their user base/customers as well.
2 billion records will then become a very big problem for you and your business as a cloud service provider using the agile platform.
Real life example - paypal has over $2000 USD of payments flowing through its network every second. For the sake of simplicity say the average amount per transaction is $100, you would be doing ~200 transaction per second. However it is likely that you would design your database for double entry accounting.
Which would mean that for every single transaction, you would have *at least* two entries, therefore you would be doing ~400 transactions per second, after 1 minute 24000 transaction, after 1 hour 1440000 transactions, after 1 day 34,560,000 transactions and after 2 months, you would have exceed 2 billion records!
Regardless of this reaching the first billion records would take many years to reach, and you would have plenty of warning before hand, so its not a big problem right now. But it is definately a problem for cloud service providers and the future of your business as cloud service provider, using the agile platform. In time outsystems would have figured that there is a need to support int64 for cloud service providers and there is no reason not to support int64 anyways, is there? It can be done! the technology is already here, but it's not being initalised.