Are we in for another bout of political deja vu? 

To start with, the “Not wasting the coup” and “No election, no democracy” camps can merge. Laugh if you will, but it has happened before. The coup against the Chatchai Choonhavan government in 1991 only led to the military joining hands with the people it haddeemed corrupt when it seized control. A popular uprising ensued in May 1992 and the Democrats laughed their way to power.
A Prayut-Pheu Thai alliance may be more unimaginable than the infamous Suchinda-Samakkhitham partnership that triggered the 1992 May Crisis, but General Prayut Chan-o-cha and General Suchinda Kraprayoon apparently have one key thing in common. They both want (or wanted, in Suchinda’s case) to stay on as prime minister after a general election and oversee the politicians, the very people they abhorred (or abhor, in Prayut’s case).
To add to that, General Sonthi Boonyaratglin toppled a Thaksin Shinawatra government in a military coup in 2006, only to shrug off ridicule and disbelief to serve under a proxy government of the man he had ousted. Sonthi, therefore, “wasted” his coup and Prayut had to promise when dislodging Thaksin’s sister Yingluck in 2014 that he would never do the same.
A Prayut-Pheu Thai union, if it happens, will be subtle. We are unlikely to see Pheu Thai core members come under his wing, but don’t rule out the “small” guys, who can give him good parliamentary numbers anyhow. Thaksin’s son, Panthongtae, would not have shown such anxiety on social media had he not expected to see some Pheu Thai small fry heading Prayut’s way.
Whatever Prayut plans to do, many are seeing discouraging signs. He is being accused of luring all kinds of politicians to his side. One serious problem with that is, if the allegations are true, Prayut is making himself vulnerable to political horse-trading, which invariably leads to nepotism and leniency towards corruption.
If you find the Prayut-Pheu Thai scenario too depressing, the good news is that a Prayut-Democrat treaty is more possible and can be a lot less subtle. Don’t let the daily military-bashing by Democrat leaders fool you. In Thai politics, anybody slams anybody until after election day, and thentalks begin on how to form a coalition government.
What about the most ironic of all alliances – a Democrat-Pheu Thai tag team? Their parliamentary conflicts spilled onto the streets and ended in violence, opening the door for Prayut to roll out his tanks. The Democrats and Pheu Thai were like Uncle In and Uncle Na in a famous cautionary tale for kids. They fought over a fish (political power) and let Uncle Yoo (Prayut) be the referee. In the tale, Uncle Yoo took the best part of the fish as his pay. In real life, Prayut took all the political power.
The alliance is not likely, but it’s not impossible, either. If both parties can somehow “divide the cake” and are scared enough of Prayut, who knows?
So, what can happen next depends on who’s scared of whom the most. If a Pheu Thai landslide looms, the Democrats may have no choice but to team up with Prayut. If the general threatens to run away with the premiership and be there for a long, long time, the Democrats may be forced to do something unthinkable.
What scenario will materialise depends largely on one unprecedented constitutional rule. Purportedly designed to enforce the idea that “every vote counts”, this very rule can put Pheu Thai in a considerable disadvantage. In the past, anti-Pheu Thai votes in constituency elections in the Northeast meant nothing, no matter how massive the vote count was. Now, such votes will be put together, calculated and transformed into party list seats in Parliament for the parties of the losing candidates. 
According to some rough calculations, fewer than 80,000 such votes could yield one party list seat. (There will be no party list ballot in the next election, since all constituency votes will be combined and counted as national votes for each party.)
Some may argue that Pheu Thai could benefit from it as well, because pro-Pheu Thai vote counts have been fairly substantial in the past, including in Bangkok. One problem is that Bangkok is not as big as the Northeast, meaning Pheu Thai could live without the “every vote counts” rule.
The last-but-not-least scenario has to do with Prayut’s summary power, which will be constitutionally retained until the day the post-election Cabinet is sworn in. Some consider this a Prayut trump card, while others don’t think he will invoke it even if he’s seeing a development he doesn’t like.
As you can see, whether Prayut exercises that power or not, whether he joins hands with the Democrats or not, or whether the Democrats join hands with Pheu Thai or not, what comes next can be deja vu. It can either be simmering tension leading to an explosion of violence, or it can be deceptive calm that enables all the bad political habits to regroup and strike again.
Either way, the familiar vicious cycle beckons, and anyone romanticising the upcoming election should do so with a bit of pessimism.