In the world of cryptocurrency's it is hard to find coins that have a real value and offer a solution to a real problem. Instead of a self created problem to promote the coin.
Now one of those real life problems is how to integrate the real life world, the existing economy and market into the smart contracts of the various cryptocurrency's. There is a whole outside world with all kind of information sources. Stockprices, Plane/Festivaltickets, FIAT exchange rates, Sport results, Messaging/social media platforms, etc in the form of webservices/api's and much more ways to electronically link the information together. In the real world this information is easily available and a lot of regular services are built on top of these services. But how do we get this information into the cryptocurrency's and specifically into the smart contracts. This is the "Connectivity Problem". All the smart contracts and networks will experience this problem.
At first you think that this ins't a real problem. Because the api's and services exist, just connect to them with your smart contract and you are done. But if you actually try this you will hit the following problems.
Money. Smart contracts on any network need payment to execute. So by definition you don't want to do unnecessary work, because that costs money. Connecting to a couple of different data-sources with different technology stacks costs a lot of lines of code. That have to be executed and thus costs money.
Simplicity. Like i said, if you want to connect to a couple of data-sources with different technology stacks. That brings complexity into your smart contract. That is difficult to maintain, it can be a source for bugs and data-sources can change the api or datacontract. Thus forcing you to update the smart contract. And this is something you don't want to do often because of risks associated with that.
ChainLink solves all these problems, by providing so called "Oracles". These Oracles provide data information services to smart contracts. In this way smart contracts can connect in an uniform way to all of the "outside" information they want.
Furthermore why Chainlink is going to succeed is that Chainlink has made an proof of concept demo with the swift institution and 5 top financial firms. So it already has contact with major financial firms and made an working proof of concept.
https://www.coindesk.com/swift-startup-winner-demos-smart-contract-trade-5-financial-firms/