I plan on making both hyper/hybrid casual mobile games as well as games for other platforms. However, I will most likely start with mobile games when starting a game company. Is it feasable to have a game company that starts out making mobile games and then eventually moves on to more “hardcore” games for other platforms?

@Tom Sloper It's because the team will probably know more about casual games and mobile app development, and I don't know how successful a game would have to be to be able to afford training the entire team. For instance, a team trained for developing 2D casual games would have to learn 3D modeling as well as an entirely different engine.

It also depends tremendously on what they have built and how they have built it.

A team who builds games on Android using only Kotlin and NDK/C++, and builds their iOS games with Objective-C and Swift, they're basically locked into their platforms. Targeting a new platform will require moving to either a different platform's libraries or to platform agnostic libraries. Very few organizations do this.

These days most games use major cross-platform engines and cross-platform middleware. A team who builds their mobile games using Unreal or Unity can simply click a few buttons to target additional platforms. They may need to replace a small amount of platform-specific code and content, but perhaps 99.99% of the work is done for them since the systems implement everything in platform agnostic interfaces. While teams may need to provide a little bit of system-specific work, the vast majority can use exactly the same code and content to produce a game that runs on all the major platforms, from PC and web deployment to game consoles to phones. Unity can target 22 platforms, and Unreal can target 20. You can literally just check a few checkboxes and produce the game for all 20+ platforms.

For the specific genre and skills these will depend on the games people make. For example, if a studio is focused around 2D games and pixel art and wants to transition to 3D worlds they'll need to switch from pixel artists to modelers and texture artists. Many of their workers will likely have some amount of skill in multiple areas, so the transition for workers is going to depend on the products and on the people involved. Some can handle it immediately and are well versed in a range of tech, some can be trained and transitioned, others may need to be hired.

For some people and businesses, it is an “or”. People must decide to do this OR that.

For some people and businesses, it is an “and”. People can choose to do this AND that.

The first mindset is limiting, and sadly common. The second mindset is enabling, and it often accompanies wild growth. Over the years I've seen hundreds of companies start out as small enterprises doing tiny projects in one domain, and as time passes grow to work on many things, many projects across multiple domains. There is absolutely nothing that inherently limits a company in regards to the question in the title. (Can a casual mobile game company eventually move on to more "hardcore" games?) There are personal limitations, business choices, and financial constraints at any given time, but companies can do it, and successfully transition into additional domains quite often.