Nobody knows, because we don't know how to do it yet. There could be a "big breakthrough" tomorrow that more or less finishes it out, or it could take 100 years, or - worst case - Penrose turns out to be right and it's not possible at all.

Also, are there useful books, courses or papers that go into general AI research?

Of course there are. See:

https://agi.mit.edu

https://agi.reddit.com

http://www.agi-society.org/

https://opencog.org/

https://www.amazon.com/Engineering-General-Intelligence-Part...

https://www.amazon.com/Engineering-General-Intelligence-Part...

https://www.amazon.com/Artificial-General-Intelligence-Cogni...

https://www.amazon.com/Universal-Artificial-Intelligence-Alg...

https://www.amazon.com/How-Create-Mind-Thought-Revealed/dp/0...

https://www.amazon.com/Intelligence-Understanding-Creation-I...

https://www.amazon.com/Society-Mind-Marvin-Minsky/dp/0671657...

https://www.amazon.com/Unified-Theories-Cognition-William-Le...

https://www.amazon.com/Master-Algorithm-Ultimate-Learning-Ma...

https://www.amazon.com/Singularity-Near-Humans-Transcend-Bio...

https://www.amazon.com/Emotion-Machine-Commonsense-Artificia...

https://www.amazon.com/Physical-Universe-Oxford-Cognitive-Ar...

See also, the work on various "Cognitive Architectures", including SOAR, ACT-R, CLARION, etc,

https://en.wikipedia.org/wiki/Cognitive_architecture

"Neuvoevolution"

https://en.wikipedia.org/wiki/Neuroevolution

and "Biologically Inspired Computing"

https://en.wikipedia.org/wiki/Biologically_inspired_computin...