Alphas are ~50% subcap combat capable and ~5% mining/industry. This is intended with CCP hoping there would be many alphas blowing stuff up (or being blown up) to fix the economy that is ever more broken. But it doesn’t seem to be working.
I believe that having T1 barges wouldn’t be that much of a problem - alphas will be still limited to T1 barge using T1 strip miner with worse skills. A better miner than now, but not as good as omegas. I think there is not that much of a difference compared to say alphas using T1 BS + T1 guns for LVL4 missions instead of T2 guns and better skills to possibly run incursions too. I don’t think it is THAT much of a danger to have it AFK mining for a while.
For industry, however, having access to say 5 research slots and 10+ fab slots would simply lead to people using alpha account for industry instead. Sure, alpha clone tax makes stuff a bit more expensive, but time is now irrelevant, just buy more prints… Having 1 research slot and 4 fab ones is fine enough - enough to get the taste of that profession or self-build the cheap T1 gear for throwaway PVP, not enough to endanger the industry.
For PI, a single planet without ability to import anything or build any factory, just extractors and silos, plus poor skills likely wouldn’t be too much of a problem - only basic goods would become cheaper and there might be even some conflict over pocos due to higher volume of exports and imports. (well, assuming CCP is competent enough to turn off other PI planets and extra capability once the account lapses - so the developed planets requiring higher skills would cease to work)
But tbfh I would rather see refineries to get planet mining module and to run reactions and whatnot there. Or at least to have a linked game where you could destroy other people’s PI and defend yours.