The comparison of established technology and emergent technology on Chroma Key and Rotoscoping.
Chroma Key
Established Technology

It is evidenced that the green screen technology was invented by Larry Butler for the movie The Thief of Bagdad (1940). It was an act to reduce the cost of setting and props.

It has been one of the technology used in a wide range of production, involving the needs of physical curved green screens, set up crew members, lighting crew, green screen suit man. Also, prep artists, vfx artists and compositors are crucial roles in post production stage.
(InFocus Film School, 2017)
Emergent Technology – Virtual LED Panel
However, with emergent technology, a giant, high resolution LED panel is replaced instead of green screen. It allows directors, actors and production crew to visualise the setting during the production stage. Basically, it makes no different with a realistic on-site shooting, and even more, vfx artists can manipulate every pixels on the background artificially as early as production period.
According to Charmaine Chan, the lead compositor in Industrial Light & Magic, she used to chroma key with uneven green screen background frame by frame precisely, but with LED panel she worked with production crew simultaneously in the studio. The benefits of using it also included remaining edge details, natural color fringe in the result.
What is also worthy of our attention is that, the emergent technology established its convincible result on reflective objects. For instance, it is capable to reflect the true color lighting of what environment behinds the metallic helmet in movie of The Mandalorian. In other words, this alternative method avoid the green”spill”, which means the green edge on the objects that usually being projected by the green screen.

With this line of thinking, it is believed that the practise of using green screen in film production might diminishing as years pass, as it reflects itself as a better alternative of the established technology.
Rotoscoping
Established Technology
For animation aspect, roto technique is using to trace over motion picture footage one frame at a time to produce realistic action.
Then, silhouette is created that can be used to extract that object for another background in scene.
(Rl, 1915) (Christiansen, 2009)
The original three Star Wars movies are definitely classic examples for this traditional rotoscoping, VFX artists create glowing lightsaber effect with a matte based on sticks held by the actors.

In my self-practice of rotoscoping with Nuke X 12.2. As a beginner of using Nuke, it took me almost 7 working days for a 4s output.
Every frame needs to be pixel-perfect, which required huge manpower and hours to work on it. In VFX industry, this kind of specific professional job task is the role of roto artists, who employing by studio to work on matte footage.
Emergent Technology – Machine Learning
However, with emergent technology of machine learning, RunwayML appeared to be a time-saving tool for vfx artists to obtain the same results instead of rotoscoping. With machine learning, the objects can be painlessly identified and altered frame by frame accordingly for being background masked out.
Referring to the Youtube video created by Boone Loves Video, it indicates that every users can learn to apply this technic with only basic knowledge of using adobe software as assistant. It also mentioned that the up coming version of RunwayML is expected to perform even further ahead, while it is only a new launch platform in its developmental stage.

In sharp contrast with my previous rotoscoping experience, I only took less than 10mins to get a satisfied result from accessing RunwayML.
That is no doubt that this ever-changing post production industry will persevere to flourish, and every video creators certainly noticed the positive sides of this emergent technology.
Reference
1. Christiansen, M. (2009). Adobe After Effects CS4 studio techniques. Berkeley, Ca: Peachpit Press, Cop.
2. Rl, P. by M.F., artist unknown; cropped/retouched by (1915). English: Patent drawing for Fleischer’s original rotoscope. [online] Wikimedia Commons. Available at: https://commons.wikimedia.org/wiki/File:US_patent_1242674_figure_3.png
3. Vincent, J. (2019). Creators now have an easy way to incorporate AI into their workflow. [online] The Verge. Available at: https://www.theverge.com/2019/7/10/20682307/ai-machine-learning-easy-to-use-models-creatives-runway-ml
4. InFocus Film School. (2017). Filming With Green Screen: Everything You Need To Know. [online] Available at: https://infocusfilmschool.com/filming-green-screen-guide/.
5. Vox (2020). The technology that’s replacing the green screen. Vox. Available at: https://www.youtube.com/watch?v=8yNkBic7GfI.
6. Boone Loves Video (2021). [online] Available at: https://www.youtube.com/watch?v=wBkDdZYPj64.