Well, it's not as surprising as it seems - right now the BC Liberals are sitting below 30% in my polling average, so you may want to brace yourself for more floor crossings.
But what surprises me about John van Dongen's floor crossing is not necessarily that he did it - just when he did it.
van Dongen was upset with the Clark government, and his riding of Abbotsford South would be a prime Conservative target. But at the very least you think that he would wait until after the recently-called by-elections in Chilliwack-Hope and Port Moody-Coquitlam, where the actual mettle of John Cummins' Conservatives would be challenged. After all, we don't know if the Conservative rise in BC is a blip or something more serious than that. We would get a better picture after the by-elections.
I mean, he could have simply left and sat as an independent, something which BC MLAs are fond of doing when they're dissatisfied. van Dongen instead chose to become the sole MLA for a party that, while maybe he'll feel ideologically comfortable in, still places him under a label that, if he chose to run again, he'd have to settle with. Rationalism would dictate you wait to see what happens, but who said politicians are rational?
Short-term effects are more bad press for Premier Clark, and she has enough of it already. Long-term effects... well, hard to gauge. This is like when Scott Brison crossed the floor to the Liberals - it signified dissatisfaction with something, gave the Cons bad press, but in the long run, the electoral fortunes of the Liberals still dwindled anyways. Same goes with the three Wildrose MLAs that crossed the floor from the PCs in Alberta.