Is there an alternative for flash out there?
Sure, HTML5 for instance, but whatever site hosting the content has to make it available. It's not something you can do on your own, other than to refuse to patronize the sites that are too lazy to update their content.
It's like this: Adobe Flash Player doesn't run on iOS. If a website or content provider doesn't care enough to make their content available to the hundreds of millions of iPads and iPhones out there, they're not serious about distributing their content.
Your MBP can handle a lot of heat, more than would be comfortable for you to hold, which causes understandable concern. Thermal protection consisting of hardware and firmware independent of the MBP's operating system will shut it down if required.