The simple answer, I'm afraid, is don't buy a TOC specific ticket.
Are you saying don't buy an Advance then?
When a passenger buys a ticket and complies with all the rules and then one leg of their journey is heavily delayed or cancelled or even delayed by 8 mins* and a connection is missed is that their fault?
Should they be further inconvenienced by having to wait potentially a further two hours to travel on the next TOC specific? This could cause them in theory to miss the last connection of the day to their final destination. I see advance tickets from Cornwall to Scotland on a daily basis, as no doubt do you also, these journeys are time critical, one missed connection can scew them up - having to wait longer for a TOC specific - could be catastrophic!
A few examples will suffice then I'll give you my views.
i)* My Dundee - Edinburgh which offers a 5min connection into a TPE service at Haymarket is late. (Held at Dundee to allow passage of late 1B16 Inverness - Edinburgh delayed due to signal problems at Kennethmont; lost path so held at Tay Bridge (High Girders) to allow EC LDS - ABD to pass - now 12 mins down). Driver made valiant effort to make up time. I had passengers doing parachute rolls alighting at stations to save time - to no avail. Connection not held.

I had 20+ pax for the TPE most on TPE & Connection advances. Next TPE almost 2hrs later - next Virgin about 50mins later. I could not guarantee that the Virgin would take them - lots of unhappy punters. :cry: but I did endorse all tickets with details of delay. How much better would it have been if I could inform them that yes the Virgin would take them as matter of routine.
ii) I'm standing on the Platform at Lancaster after a good day out with a friend travelling on a £5 First Group Friends & Family ticket. Next TPE to Edinburgh is cancelled - a two hour wait ensures - well not quite as a Virgin train pulls in- Guard recognises me, comes over for a quick chat & asks what I'm doing - when I tell her about the cancelled train she says jump on I'll not see a colleugue stranded. What about my mate and showed his ticket to her (it was before those horrible print at home jobs) - he can come too was the answer. Result. I put a few quid though the till at the shop so Virgin would get a few pennies. The Guard told me she picked up a few TPE advance holders at Oxenholme/Penrith but as it was freezing cold by then she allowed them to board.
The moral of the story is this. When everything is running ok we may be in competition with each other BUT when the proverbial hits the fan we should work as ONE railway. After my experience on that Virgin train I never refuse a Virgin ticket holder travel on my train if they have experienced delay/disruption/cancellation enroute. The goodwill generated by that guard I have repayed 10 fold to Virgin Pax over the years.
As a general rule I prefer passengers who are not booked on my trains to ask first and they don't get priority over our own ticket holders. As a regular traveller myself I have experienced my fair share of delays and know first hand what a nightmare it is when TOC's can't agree an action plan. On the other hand when they work together - traincrew, station staff, control from all affected TOC's it can make such a positive difference.
If your RyanAir flight is cancelled would you expect to wait for the next RyanAir flight or would you expect to catch the next available flight which might be British Airways?
Its the same principle unfortunately, but where TOCs are better is that at times of serious disruption they will allow passengers to transfer.
Proper airlines take each others passengers in times of disruption. Its happened to me a few times. They all pay into a common fund for such inevitabilities. Ryanair (tightwads) do not so they're not in the scheme. It's one of the reasons that proper airline tickets are that wee bit more expensive.