Transformers will be going on for at least 30 more years or until Trump nukes China. For all their faults they are slowly getting to that "Fast and the Furious" retarded fun phase with King Arthur and shit, so chances are that sooner or later, or when Bay finally goes away from the main series, that it'll get better.
TMNT is just a waste all around but Turtles, unlike the other two, have a far better overall franchise history, with the original comic being amazing, the '86 cartoon being goofy fun that's still surprisingly watchable, one fucking amazing movie, one goofy cool movie, an AMAZING revival 2003 series, a GLORIOUS TV crossover movie, a pretty ok new cartoon and a modern IDW comic run that is just balls out amazing even if I'm not fan of the most of the art.
So really two shit movies don't do the franchise that much disservice, it'll just go in the same pile with the Next Mutation and the 3rd movie.
Rangers I like transformers were never good. The concept is good, the designs are cool, it has like one or two good story arcs, but overall it's just shit. This movie failed to capitalize on the super hero hype train, failed to capitalize on the goofy fun humor train, failed to capitalize on nostalgia and was overall just a horrible mess. It it came out in like 2005 (the CGI looks like it's from 2005) it'd probably be great because it's made in the spitir of pre-MCU movies. This way it's just a bizarre visitor from another time, like the Masters of the Universe movie only shittier.
It also flopped hard so there probably won't be any more.