Many people criticize string theory for being very speculative and far fetched (since it requires extra dimensions). Nevertheless, the string landscape is often invoked to have many variations of constants in different regions of the inflationary multiverse since ordinary GUTs only allow small variations:
"The fundamental theory of nature may admit multiple vacua with different low-energy constants. If there were just a few vacua, as in standard GUT models, then a few observations would determine which one corresponds to the real world. Predictions would then follow for every other observable in the low energy theory. However, it has recently been realized that in the context of string theory there may be a vast landscape of possibilities, with googols of vacua to scan."
Alexander Vilenkin, "Probabilities in the inflationary multiverse" (2005)
"While the multiverse is rooted in the cosmological concept of eternal inflation (Vilenkin 1983), the string landscape is necessary for providing a physical basis for allowing different values of the cosmological constant and other parameters in each universe of the multiverse."
Richard Dawid, "Philosophy of String Theory" (p.9)
My question is the following: are there alternatives to the string landscape that allow for many variations of constants? Is the string landscape necessary at all to have variations in different inflationary regions?