Quick Question on the Plausibility of a Sound Change

[Das Baron]

I've been playing around with a conlang idea recently, and part of the sound changes is getting rid of all /Cw/ clusters. So far I've got the following:

/kw/ -> /t/ (before a front vowel), /p/ (before a back vowel)
/gw/ -> /w/
/tw dw/ -> /p b/

All of which are attested in natural languages, so they're not really a problem. However, earlier in the language I have /sw/ -> /hw/ [ʍ], which changes with the group above to mirror the development of /kw/: /hw/ -> [θ] (before a front vowel), /f/ (before a back vowel). It seems pretty reasonable to me, but I know of no examples of it happening in any natural languages. Is it plausible, and do any natural languages show it?

[alice]

I've been playing around with a conlang idea recently, and part of the sound changes is getting rid of all /Cw/ clusters. So far I've got the following:

/kw/ -> /t/ (before a front vowel), /p/ (before a back vowel)
/gw/ -> /w/
/tw dw/ -> /p b/

All of which are attested in natural languages, so they're not really a problem. However, earlier in the language I have /sw/ -> /hw/ [ʍ], which changes with the group above to mirror the development of /kw/: /hw/ -> [θ] (before a front vowel), /f/ (before a back vowel). It seems pretty reasonable to me, but I know of no examples of it happening in any natural languages. Is it plausible, and do any natural languages show it?

I don't see why it shouldn't be plausible; it parallels the development of /kw/, after all, which is good enough for me

[spats]

I've been playing around with a conlang idea recently, and part of the sound changes is getting rid of all /Cw/ clusters. So far I've got the following:

/kw/ -> /t/ (before a front vowel), /p/ (before a back vowel)
/gw/ -> /w/
/tw dw/ -> /p b/

All of which are attested in natural languages, so they're not really a problem. However, earlier in the language I have /sw/ -> /hw/ [ʍ], which changes with the group above to mirror the development of /kw/: /hw/ -> [θ] (before a front vowel), /f/ (before a back vowel). It seems pretty reasonable to me, but I know of no examples of it happening in any natural languages. Is it plausible, and do any natural languages show it?

So to clarify, you have:
ʍ > f / _V[+back]
ʍ > θ / _V[+front]

The first is very plausible. The second is more plausible in my mind if the starting sound is xʷ and /t/ and /d/ are dental. I'd more expect ʍ (rather than xʷ) to go to ʃ, ç, or ∅ before a front vowel in your scheme. Likewise, if /t/ and /d/ are strictly alveolar, I might expect ʍ or xʷ to go to something like s instead.

But sound change is weird, and anything can happen. There's certainly nothing wrong with what you've posited.

[Wattmann]

Since it is triggered by front vowels, most likely the sound will become some sort of sibilant.
Thus, if you seriously want /θ/, it might look something like:

ʍ > θ^s > θ/ __V[+front]

Where θ^s is some sort of sibilant dental.
Since that would require you to have more dental /t/ and /d/, you might also want this:

{t d} > [-Alveolar][+Dental]

Thus giving you:

{t d} > [-Alveolar][+Dental]
ʍ > θ^s > θ/ __V[+front]

The first ones is quite neccesary because new sounds tend to gravitiate to already used points of articulation, if such a slot is unused.
Or, if you have an ambiguously positioned /t/ and /d/, you might get away with a /θ/ : /s/ distinction (as English does) without really having to change the POA of the plosives.

As for ʍ > f, you'd also need an intermediary stage, so something like this happens:
ʍ > ɸ > f/ __V[+Back]

This is readily attested.