SQLite takes more of the imagination
Your question starts from a false premise. First this is a value thought about 10, 15 years ago and was well, very conservative, and does not consider proper techniques to increase that capacity. SQLite has improved a lot since then, hardware has improved, it has thought of other techniques and in practice it has always been able to do more. It's really nonsense to have put that number down there on the product page.
Note that the official page is talking about a web server rather than a mobile device that you do not even have concurrent access to. In fact, the page says that only 1% of websites are not appropriate. So it's another false premise.
My experience is that in fact 0.1% is not suitable for SQLite, if used the right way. Do you think it will be one of the 1% most successful sites in the world? That means you will be one of the 10 or 20 largest Brazilian sites. Even if one day this happens, you will have so much money coming from this site that you can hire the best professionals and compare the best tools to solve your problem.
To tell you the truth I think it is naive to post this value, because the capacity can not even be measured in this way, it has several false premises in this information.
Even the most sophisticated databases often need ancillary tools, adequate techniques to handle. This site you are using right now is one of the 25 most accessed in the world. It uses SQL Server, but the ability to fulfill all of this is not because SQL Server is excellent, it's because the engineers who take care of the site are excellent. Has much smaller site that used SQL Server, Oracle, MySQL, and other things and opened the beak. Because? Whoever did did not know what he is doing. Without understanding how things work any tool may be the wrong one.
See more about where it can really be used .
You can always change the database, but I doubt it will ever be necessary even if you use SQLite on the web server. If it is to use in mobile never have to change, because the hardware of a cell phone can not handle doing so much operation, SQLite is less of your problems. But I guess you're just saying this because you think you'll have thousands of connections on a mobile device. And it's more a false premise.
If you are thinking that people will install MySQL, Oracle, etc. on their cell phones, you are very much mistaken. Not that I can not, but it's crazy that I've never seen anyone sweating.
As already mentioned, SQLite can handle millions of requests per day if used correctly. This is more than almost every site in the world needs. But if on the server you want another DB, and there are even reasons for this, but not because SQLIte is not good, the most used for web is MYSQL, although many people are preferring MariDB which is a fork of MYSQL.
You can also use other relational banks or not, but the decision of the correct tool goes through a deep analysis of very experienced people to get it right. If you're having trouble with something so basic, it's best to go with the simplest (SQLite) and hire expert people when you need something sophisticated.
It's what I always say, people need to learn how things work, check it out on their own, and not believe what's written there, most of the information available on the internet is wrong. Because there is little canonical information, and even these may be wrong, as is the case, and there are copies of the canonical information misrepresented, such as a cordless phone.