I was originally going to suggest the old "What if Future Trunks was trapped in the past" idea for this thread, but lets be honest - most people have already done variations of it.
So, I decided to look at the flip-side for this brainstorming session:
- The story proceeds as normal, with Future Bulma in the alternate timeline finishing the Time Machine and having it fueled up before Future Trunks takes it back to the past; intending to warn everyone there about the Android threat and give Goku the Heart medicine.
However, with Bulma working with limited resources on her own and with the stress of the two murderous Androids potentially finding her and Trunks (especially considering said Androids wiped out the other Z-Fighters, nearly killed Trunks when he took them on alone and probably killed her parents and sister as well), she fails to notice a flaw in the machinery.
- When Future Trunks goes back to the past, he arrives safely and does his usual routine - killing Mecha-Frieza, King Cold and their mooks before meeting up with Goku to give him the warning and the Heart Medicine.
When he lifts off in preparation to return to his timeline, however, the earlier flaw - exacerbated during the first Time Travel journey - reveals itself in spectacular fashion; an explosion ripping through the Time Machine before a fire breaks out inside and causes it to crash-land.
While Future Trunks gets out, his Time Machine is toast - and with no schematics/notes for the current Bulma to make a new one from scratch or figure out the flaw if they ask Shenron to magically repair it. So, Future Trunks is now stuck in the past.
- In the alternate timeline, Future Bulma waits for her son's return...but a week goes by, then two, then three, then a month. It quickly becomes clear to Bulma that something has gone wrong (and I can imagine her been distraught over not knowing if her son is dead or stuck in another timeline, as well as wracked with guilt over the fact that she is responsible for it).
Question is, now she's on her own, do you think she would find a way to survive by herself - even if Future Cell rocks up?
Could she find a way to rectify the situation without relying on those with Saiyan blood (be it heading into space to find New Namek, contacting the Galactic Patrol or gathering the materials for another Time Machine so she can attempt to retrieve Future Trunks herself)?
Or, do you think this is a hopeless situation for her and she would inevitably meet her demise?
Curious to see what you guys think.