UK cell tower and TV mast operator Arqiva has been put up for sale with an optimistic price tag of between £5bn and £6bn, even though its two core areas of business have question marks hovering over them. Any mobile tower company taking a long hard look at 5G has to decide whether it can extend its model into small cells. These will be an increasingly large percentage of mobile roll-out, putting pressure on the macro tower business, but they require significant changes to the traditional infrastructure business model – different payback cycles; a low price/high volume asset base; and the likely requirement, in some markets, to support active as well as passive equipment. Some towercos, like Crown Castle in…