Saying that Huygens "wasn't much" and "was just a part of the larger Cassini mission" is pretty misguided thinking and borders on insulting the scientists and engineers who put this amazing probe together, IMHO.
Are you saying that designing a probe that survives, dormant, for almost 7 years in interplanetary space and then turns on perfectly "isn't much"? Are you saying that making a fully-autonomous descent and soft landing on an outer planet's moon and sending back a stunning image of the surface "isn't much"? Are you saying that providing essentially real-time (light travel delay notwithstanding) imaging of lakes and drainage gullies during the descent, along with atmospheric sampling, "isn't much"? Are you saying that getting all these signals back from 1.2 billion kilometres with just a 10 watt transmitter "isn't much"? Good grief.
It was also much more than "just" a part of the Cassini mission: it was an integral part of it, all the way back to the early 1980s when the joint mission was first proposed. The US-European collaboration had its political moments, but it worked. Yes, Cassini is still returning great data (including the Titan sea glint image), but Huygens was never going to survive long with just batteries to power it under Titan's atmospheric murk. It shouldn't be dismissed as a consequence.
As for TSSM, it's a massive overstatement to say that it's "scheduled": nowhere near. TSSM (or more properly, its TandDEM predecessor) was proposed to ESA as a large (L) mission as part of the Cosmic Vision process in 2007 and did go through to the beginning of the second round along with the (also joint ESA-NASA) LAPLACE mission to Jupiter. The latter was however chosen for study by ESA and NASA to pursue first and is now the Europa Jupiter System Mission (EJSM). EJSM, if selected as the first CV L-mission, would fly (probably) no earlier than 2020, thus pushing TSSM back to the mid-2020's at the earliest, with arrival at Saturn and Titan in the mid-2030's.
So, exciting as it would be scientifically, don't hold your breath.