It is not necessary to shift from Qlikview to Qlik Sense.
Both the tool have their different use cases.
1. QlikView -
Used for guided analytics
Best product when you want to have pixel perfect reporting.
2. Qlik Sense-
Its more useful when you want to give self service.
Best product for integration with other tools and technology.
and many more.
So you need to decide what is your use case and choose product accordingly.